The Battle of Trafalgar was fought between British and Franco-Spanish fleets on 21 October 1805. A force of 27 British ships of the line faced 33 allied ships. Both forces were formed in two columns; the British sailed parallel, the allied one following the other.

The Battle of Trafalgar was fought by sailing vessels and therefore cannot be understood in substance except as the manoeuvring of sailing vessels according to the principles of sailing.^{[citation needed]} Without understanding the importance of wind and weather, especially wind direction, the modern can make no sense of the manoeuvring. Once those principles are understood, the plan of battle unfolds in a transparent fashion. The plan is included here as well as its general applicability to real events.

Real battles do not always develop according to plan, or exactly according to plan. Commanding officers usually are empowered to respond to the battlefield situation as it develops. Such concepts as "sailing order" and "battle order" are constructs. In a column of ships sailing anywhere the first ship forward was Number 1, the second, Number 2, etc. The battle order was based on planned order of attack.^{[citation needed]} Ships were assigned places in these orders by the commander, sometimes temporarily or even extemporaneously.

Nelson used the order that was best momentarily. In stormy weather or other adverse conditions the commanders might not be able to control the order. "Nelson's fleet" was not a fixed entity; ships were continually joining or leaving his fleet for various reasons: for example HMS Superb, was in the docks being repaired after four years at sea, including the chase of Villeneuve and was daily expected to re-join the fleet, where her Captain, Richard Goodwin Keats was to be Nelson’s second, but she was not repaired in time.^[1] The complements of the ships also were variable. The early historians of the battle were not sure of what they were, nor did they know exactly what the casualties were.^{[citation needed]} The roster lists of the ships before sailing were generally used. Afterward there were plenty of reports.

The numbers and orders of this article are based on the figures of modern scholars for the most part. There is general disagreement on the exact order and the exact numbers, but, on the whole, the different estimates are close to each other and can probably be taken as accurate within a few per cent.^{[citation needed]} An effort is made to keep consistency between the tables and the graph.

The plan of battle from a sailor's point of view

The constraints of sailing and sailing vessels

The combined French-Spanish fleet left Cadiz harbour in a loose line and turned to the south along the coast of Andalusia, headed for Naples through the Straits of Gibraltar. They were taking advantage of the north-westerly wind which was blowing on the starboard (right) rear quarter, nearly amidships, pushing them along at a slow rate and causing a swell (waves) perpendicular to the wind direction. It struck the ships from the side, causing them to roll and ruining their stability as gun platforms. The column had a predetermined order, which was necessary for sailing, to prevent some ships from getting between the wind and other ships, "stealing" their wind and running the risk of collision.

The same wind that was moving the French and Spanish south was also bringing the British north. A sail is basically an airfoil. When full it is curved in such a way as to create a sideways "lift," or force perpendicular to its surface, one component of which is actually against the general direction of the wind. A sailing vessel can thus sail "into the wind." A keel prevents the ship from "slipping," or sliding sideways along the wind. The sails "are full;" that is, fully curved, only at certain angles to the wind direction. The angle is adjustable via "sheets," or lines, which generally have to be winched from the deck. The force required is high,^[2] giving rise to the idea that one is "hauling" the ship into the wind, and therefore the ship is "close-hauled." When not full, the sails flap uselessly in the wind, or "luff." The sailors must then change the angle, or "trim the sails," until they fill.

A square rigged ship cannot sail within 6 points (67.5 degrees) either side of the wind. If the wind is coming from the north, the closest it could sail would be ENE or WNW. In order to travel in that direction, it must "fall off," or move to an angle with the wind on one side or the other, a "tack." A ship tacks back and forth against the wind, or "beats," each tack earning it some "headway". However, because of the huge distance a square-rigger had to travel before it could fill its sails again, tacking would only be done in a dire emergency; where speed of manoeuvre outweighed the enormous risk of being caught in irons. By far the most common way of working to windward was wearing round (gybing).

In addition, sailing with the wind directly aft ("abaft") or directly on either side ("abeam") was difficult and inefficient. Sails with the wind in those directions do not fill. The wind must be allowed only from the quarters. At those angles the sails fill and there is a component of force in the desired direction. If the wind is directly abeam, the ship must fall off or close up. The ship may sail on either side of a wind directly astern. A manoeuvre similar to coming about is used to move the wind from one side to another: wearing. The helm is put over, the sails go limp, they are adjusted to fill on the other side. The ship does not have to rotate as far, so the manoeuvre is less disruptive.

Wind is everything to a sailing vessel. It cannot move anywhere without it (is "becalmed"). If the wind is too great the sails may have to be shortened to present less area, a procedure call "reefing." In a storm the ship must sail close to the wind or have it close astern. As the waves are generally coming in with the wind, a ship sailing close into the wind generally cuts them perpendicularly and only pitches; i.e., drops into the troughs and rises on the crests. A ship with the storm wind abeam is struck longitudinally and rolls treacherously, running a risk of capsizing. To avoid that risk the captain must run before the wind. All directions are evaluated with regard to the wind. The side of a ship toward the wind is called the "weather" or "upwind" side; away, the "lee" or "downwind" side (refer to Windward and leeward).

Much has been made of the tactics of various great sailing captains, but the greatest constraints come from wind direction and relative position. The captain of a steam vessel has considerably more freedom to take his ship where he wishes to take it, but the tactics of a sailing captain are to a large extent already predetermined by nature. To get to any point the sailing captain must plot a course taking wind direction into consideration. He must have judgement and skill, and is evaluated by the men on that skill.

Nelson's plan of battle

Nelson's battle plan is revealed on a surviving "memorandum" to his captains scrawled on a sheet of paper. The memorandum was meant to be official, as it is signed "Nelson and Bronte"^[c] and dated "Victory, off Cadiz, 9th October, 1805," which was 12 days before the battle on the 21st.^[3] Nelson and his fleet were patrolling off Cadiz, waiting the exit of a combined French and Spanish fleet. He knew better than to attack a heavily fortified harbour, the most heavily fortified in Spain. Meanwhile Nelson was staying out of sight and out of reach.

Sailing ships were not amenable, compared to modern ships, to this type of combat; they moved in slow motion at the mercy of wind and wave. A fleet of ships could deliver the most fire without risking hitting one of their own when it was sailing broadside in a line to the enemy, hence the designation "ship-of-the-line" for heavy ships of 50 or more guns. In variable weather, the manoeuvring required to set up a line could cost "... such a loss of time that the opportunity would probably be lost ...."^{[citation needed]} While the attackers were manoeuvring, the targets might escape. Nelson therefore, had his fleet sail in order of battle.

In order "to make the business decisive," Nelson would attack on sight, going directly for the enemy line. This tactic was not standard, but neither was it new or unusual. The plan was revealed to one of Nelson’s favourite captains, Richard Goodwin Keats, in an animated conversation while the two were walking in Nelson’s garden at Merton just weeks earlier.^[4][5] It did have a drawback. Only the front of the attacking column could engage. Nelson's 27 ships-of-the-line would attack in two columns. If they succeeded in breaking the enemy line, they could then take on the enemy piecemeal.

The general orders from Nelson were to "make the attack upon the enemy, and to follow up the blow until they are captured or destroyed."^{[citation needed]} If individual ships were momentarily lost in the confusion, they could do no better, said Nelson, than to pull alongside an enemy and fight broadside.

Once the enemy was in sight, the British fleet would form two columns. The double column would be sailing with the wind on one side, the windward or weather side. The columns were thus described as the "weather column" or the "lee column." Nelson would take command of the weather column while his "second-in-command" would take the other. The second could act independently. However, at that time Nelson did not know which side would be the weather side. That detail could not be decided until they were on the expected final approach. At that time the second half of the single line would sail along the leeward side of the first.

As they sailed, the wind could be anywhere on the weather side, from bow to stern. It could not be from a disallowed direction. If, reasoned Nelson, the enemy fleet was first seen to windward, it was probably extended so that the van (front) could not help whatever was behind it. Such a scenario implies the enemy stretched across Nelson's port bow quarter moving anticlockwise, but he did not know where the wind would be. His column would either be able to fetch^[d] the enemy column or not. If not, the opportunity was lost; they would have to fall off to leeward, wear, and come up on the other side, by which time the hoped-for battle would be only a pursuit.

If they could fetch the enemy on the current tack, they were to turn to port perpendicular to the enemy column (or near it). The lee column would now be facing the enemy's rear. Taking a bearing on the 12th ship from the end, they were to sail through to it, while the weather column sailed through to the centre. The 20 ships to the front were to be ignored. Nelson hoped to destroy all the ships to the rear before the enemy's van could wear round and join the battle. They were hoping to capture Villeneuve, whom they supposed to be in the centre. If the enemy van tacked or wore in an effort to stage a rescue, the British fleet would station itself between them and the captured and disabled ships, and defeat them in further battle.

If on the other hand the enemy fleet was first seen off the lee side; that is, off the starboard bow, the British would be in the strongest position. Turning to starboard they could glide downwind to the enemy and strike him wherever they pleased. Nelson seems to have believed the enemy line would have the same direction of travel, anticlockwise around the British line. Thus the lee line would act by the same instructions, turning to starboard, sail through to the 12th ship from the end.

As luck would have it, in the real battle, the enemy appeared to the lee. However, they were sailing clockwise around the British fleet, forcing the weather column to attack their rear^{[citation needed]}. The real situation changed rapidly as the enemy column reacted but the direct attack on the centre and doubling of the column were planned and resulted in victory.

Matching the plan to the real battle

The French and Spanish were crowded into Cadiz Harbour, protected by shore batteries. Nelson entertained briefly a proposal to sail up to the entrance to the harbour and saturate it with the new Congreve Rocket, setting the enemy ships on fire. That is exactly what Villeneuve was hoping they would do. He believed the combined fire of shore and ship was the best chance of destroying Nelson. He delayed, hoping to exploit any impetuosity and impatience the younger commander might evidence.

Nelson's link to the enemy was an unobtrusive line of spy ships. The enemy saw only the first in line observing them at a distance. That ship was in signal range of another, which was in range of another, all the way back to Nelson, wherever he happened to be.

Higher-level decisions were being made by Napoleon, who could not wait indefinitely for the opportunity to invade Britain, and who had switched his attention to war on the continent, especially Austria and Italy. He needed Villeneuve in the Mediterranean and issued an order to sail out of Cadiz immediately.

Napoleon however, was not as skilled in naval matters and imagined that a fleet of 40 or so large vessels could leave port in an instant. It could take a considerable time for that many ships to get out of port, even under the best conditions. Moreover, they could not do so without favourable winds. If the winds were fickle, progress would be even slower and if the winds were contrary, the whole operation would be impossible.

British fleet

The table below shows the British vessels as they were deployed just prior to engagement. HMS Africa, somewhat detached to the north due to a combination of weather and a missed signal during the night, was supposed to have been fourth from last, in the lee column.^{[citation needed]} The rest of the ships-of-the-line were divided into two columns, with the weather column forming the northern flank and the lee column the southern flank. The enemy line had been sailing north to south in front of the wind. Just as the battle was beginning they turned individually anticlockwise, wore ship, and came into the wind, hoping to bear down on Nelson. The order of British ships in the table is the one of that moment. Prior to closing with the enemy, they were in a single line, and after engagement, the ships manoeuvred to assume the best firing positions. The British fleet of the battle consisted of 33 warships, 27 of which were ships of the line.^[6] During the battle the frigates (which had been the force observing Cadiz) and smaller vessels acted in support to the fleet, relaying messages and towing ships but did not engage. When Collingwood took command after Nelson's death he transferred to Euralyus as his own flagship, the Royal Sovereign, was badly damaged.

British fleet ^[7]

Ship	Type	Guns	Fleet	Const- ruction	Commanded by[e]	Complement	Casualties
							Killed	Wounded	Total	%
Attacking the Head of the Franco-Spanish Fleet
Africa[9]	2-decker	64			Capt Henry Digby	498[10]	8[11][f]	44	52	10%
Weather column
Victory[12]	3-decker	104			Vice-Admiral Lord Nelson † Capt Thomas Masterman Hardy	821[g] nominal 850	57	102	159	19%
Téméraire [13]	3-decker	98			Capt Eliab Harvey	718[14] nominal 750	47	76	123	17%
Neptune[15]	3-decker	98			Capt Thomas Fremantle	741[16]	10	34	44	6%
Leviathan[17]	2-decker	74			Capt Henry William Bayntun	623[18]	4	22	26	4%
Conqueror[19]	2-decker	74			Capt Israel Pellew	573[20]	3	9	12	2%
Britannia[21]	3-decker	100			Rear-Admiral Lord Northesk Capt Charles Bullen	854[22]	10	42	52	6%
Agamemnon[23]	2-decker	64			Capt Sir Edward Berry	498[24]	2	8	10	2%
Ajax[25]	2-decker	74			Lieut John Pilford (acting captain)	702[26]	2	10	12	2%
Orion[27]	2-decker	74			Capt Edward Codrington	541[28]	1	23	24	4%
Minotaur[29]	2-decker	74			Capt Charles Mansfield	625[30]	3	22	25	4%
Spartiate[31]	2-decker	74			Capt Sir Francis Laforey	620[32]	3	22	25	4%
Lee column
Royal Sovereign[33]	3-decker	100			Vice-Admiral Cuthbert Collingwood Capt Edward Rotheram	826[34]	47	94	141	17%
Belleisle[35]	2-decker	74			Capt William Hargood	728[36]	33[h]	94	127	17%
Mars[37]	2-decker	74			Capt George Duff † Lieut William Hennah	615[38]	27[i]	71	98	16%
Tonnant[39]	2-decker	80			Capt Charles Tyler	688[40]	26	50	76	11%
Bellerophon[41]	2-decker	74			Capt John Cooke † Lieut William Pryce Cumby	522[42]	28[j]	127	155	30%
Colossus[43]	2-decker	74			Capt James Nicoll Morris	571[44]	40[k]	160	200	35%
Achille[45]	2-decker	74			Capt Richard King	619[46]	13	59	72	12%
Revenge[47]	2-decker	74			Capt Robert Moorsom	598[48]	28	51	79	13%
Polyphemus[49]	2-decker	64			Capt Robert Redmill	484[50]	2	4	6	1%
Swiftsure[51]	2-decker	74			Capt William Rutherfurd	570[52]	9	8	17	3%
Dreadnought[53]	3-decker	98			Capt John Conn	725[54]	7	26	33	5%
Defiance[55]	2-decker	74			Capt Philip Durham	577[56]	17	53	70	12%
Thunderer[57]	2-decker	74			Lieut John Stockham (acting captain)	611[58]	4	12	16	3%
Defence[59]	2-decker	74			Capt George Hope	599[60]	7	29	36	6%
Prince[61]	3-decker	98			Capt Richard Grindall	735[62]	0	0	0	0%
Attached
Euryalus[63]	Frigate	36			Capt Henry Blackwood	262[64]	0	0	0	0%
Naiad[65]	Frigate	38			Capt Thomas Dundas	333[66]	0	0	0	0%
Phoebe[67]	Frigate	36			Capt Thomas Bladen Capel[l]	256[68]	0	0	0	0%
Sirius[69]	Frigate	36			Capt William Prowse	273[70]	0	0	0	0%
Pickle[71]	Schooner	8			Lieut John Richards La Penotière	42[72]	0	0	0	0%
Entreprenante[73]	Cutter	10			Lieut Robert Young	41[72]	0	0	0	0%

Franco-Spanish fleet

Just before the engagement the French and Spanish ships of the line had been sailing north to south. After wearing, the order of sailing was reversed, so that the former head was now the rear. During the battle itself the entire line broke into small units and individual ships. The combined fleet consisted of 40 vessels with 18 French ships of the line and 15 Spanish ships of the line.^[74]

Ships of the French-Spanish fleet^[75][76]

Ship	Type	Guns	Fleet	Const- ruction	Commanded by[e]	Complement	Casualties				Fate	Killed in wreck
							Killed	Wounded	Total	%
Neptuno[77]	2-decker	80			Capt Don H. Cayetano Valdés y Flores	800[78]	37[m]	47	84	11%	Captured 21 Oct Recaptured 23 Oct Foundered 23 Oct	few
Scipion[79]	2-decker	74			Capt Charles Berrenger[80]	755	17	22	39	5%	Escaped Captured 4 Nov
Rayo [81]	3-decker	100			Commodore Don Enrique MacDonnell	830	4	14	18	2%	Escaped Surrendered 23 Oct (to HMS Donegal) Foundered 26 Oct	many
Formidable[82]	2-decker	80			Rear-Admiral Pierre Dumanoir Le Pelley Capt Jean-Marie Letellier[80]	840[83]	22	45	67	8%	Escaped Captured 4 Nov
Duguay-Trouin[84]	2-decker	74			Capt Claude Touffet[80]	755[85]	20[86]	24	44	6%	Escaped Captured 4 Nov
Mont Blanc[87]	2-decker	74			Capt Guillaume-Jean-Noël de Lavillegris[80]	755	20	20	40	5%	Escaped Captured 4 Nov
San Francisco de Asis [88]	2-decker	74			Capt Don Luis Antonio Flórez	657[89]	5	12	17	3%	Escaped, wrecked 23 Oct	none
San Agustin [90]	2-decker	74			Capt Don Felipe Jado Cagigal	711[91]	181[92]	201	382	54%	Captured 21 Oct Abandoned and burnt 28 Oct
Héros[93]	2-decker	74			Cmdr Jean-Baptiste-Joseph-René Poulain (DOW)[94]	690[95]	12	24	36	5%	Escaped
Nuestra Señora de la Santísima Trinidad[96]	4-decker	136			Rear-Admiral Báltasar Hidalgo de Cisneros Capt Don Francisco Javier de Uriarte y Borja	1048[97]	216	116[98]	332	32%	Captured 21 Oct Foundered 23 Oct	few
Bucentaure[99]	2-decker	80			Vice-Admiral Pierre-Charles Villeneuve Capt Jean-Jacques Magendie	888[100]	197	85	282	32%	Captured 21 Oct Recaptured 23 Oct Wrecked 23 Oct	400 on Indomptable
Neptune[101]	2-decker	80			Commodore Esprit-Tranquille Maistral[80]	888[102]	15	39	54	6%	Escaped
Redoutable[103]	2-decker	74			Capt Jean Jacques Etienne Lucas	643 (nominal 550-600)	300[n]	222	522	81%	Captured 21 Oct Foundered 23 Oct	many 172 ?
San Leandro[104]	2-decker	64			Capt Don José Quevedo	606	8	22	30	5%	Escaped
San Justo [105]	2-decker	74			Capt Don Miguel María Gastón de Iriarte	694	0	7	7	1%	Escaped
Santa Ana[106]	3-decker	112			Vice-Admiral Ignacio María de Álava y Navarrete Capt Don José de Gardoqui	1189[107] 1053 nominal	95[o]	137	232	20%	Captured 21 Oct Recaptured 23 Oct
Indomptable[108]	2-decker	80			Capt Jean Joseph Hubert †	887	20	30	50 [p]	6%	Escaped Wrecked 24 Oct[q]>	657
Fougueux[109]	2-decker	74			Capt Louis Alexis Baudoin †	755[110]	60	75	135[r]	18%	Captured 21 Oct Wrecked 22 Oct	502 (84% casualties)
Intrépide[111]	2-decker	74			Capt Louis-Antoine-Cyprien Infernet	745[79]	80	162	242[s]	32%	Captured 21 Oct Evacuated, blown up 24 Oct
Monarca[112]	2-decker	74			Capt Don Teodoro de Argumosa	667[113]	101	154	255	38%	Captured 21 Oct Burnt 26 Oct
Pluton[114]	2-decker	74			Commodore Julien Cosmao-Kerjulien	755[115]	60	132	192	25%	Escaped
Bahama [116]	2-decker	74			Commodore Don Dionisio Alcalá Galiano †	690	75	66	141	20%	Captured 21 Oct
Aigle[117][118]	2-decker	74			Capt Pierre-Paulin Gourrège[80] †	755[119]	70	100	170[t]	23%	Captured 21 Oct Wrecked 23 Oct	330
Montañés[120]	2-decker	74			Capt Don Francisco Alsedo y Bustamante	715	20	29	49	7%	Escaped
Algésiras[121]	2-decker	74			Rear-Admiral Charles-René Magon de Médine † Cmdr Laurent Tourneur[80]	755[122]	77	142	219	29%	Captured 21 Oct Recaptured 23 Oct
Argonauta[123]	2-decker	80			Capt Don Antonio Pareja (WIA)	798[124]	100	203	303	38%	Captured, scuttled 21 Oct
Swiftsure[125]	2-decker	74			Capt Charles-Eusèbe Lhospitalier de la Villemadrin[80]	755[126]	68	123	191	25%	Captured 21 Oct
Argonaute[127]	2-decker	74			Capt Jacques Épron-Desjardins[80]	755[128]	55	132	187	25%	Escaped
San Ildefonso[129]	2-decker	74			Capt Don Jose Ramón de Vargas y Varáez	716 [130]	34	148 [u]	182	25%	Captured 21 Oct
Achille [131][118]	2-decker	74			Capt Louis-Gabriel Deniéport †	755[132]	480	?	480	64%	Surrendered, blew up 21 Oct
Principe de Asturias[133]	3-decker	112			Admiral Don Federico Carlos Gravina (DOW)[v] Rear-admiral Don Antonio de Escaño Commodore Don Ángel Rafael de Hore	1113	54	109 [w]	163	15%	Escaped
Berwick[135]	2-decker	74			Capt Jean-Gilles Filhol de Camas[80] †	755[136]	75	125	200[x]	26%	Captured 21 Oct Foundered 22 Oct	622
San Juan Nepomuceno[137]	2-decker	74			Commodore Don Cosmé Damián Churruca y Elorza †	693[138]	103	151[y]	254	37%	Captured 21 Oct
Attached
Cornélie [139]	Frigate	40			Capt André-Jules-François de Martineng[80]	?	0	0	0	0%	Escaped
Hermione[140]	Frigate	40			Capt Jean-Michel Mahé[80]	?	0	0	0	0%	Escaped
Hortense[141]	Frigate	40			Capt Louis-Charles-Auguste Delamarre de Lamellerie[80]	?	0	0	0	0%	Escaped
Rhin[142]	Frigate	40			Capt Michel Chesneau	?	0	0	0	0%	Escaped
Thémis[143]	Frigate	40			Capt Nicolas-Joseph-Pierre Jugan[80]	?	0	0	0	0%	Escaped
Furet[144]	Brig	18			Lieut Pierre-Antoine-Toussaint Dumay	130	0	0	0	0%	Escaped
Argus[145]	Brig	16			Lieut Yves-Francois Taillard[146]	110	0	0	0	0%	Escaped

Losses

Below is a graph of the percentage of casualties plotted for each ship along the three battle columns. The graph is a construct only. The losses were incurred throughout the entire battle and after, most while the ships were not actually in that order. The order in the graph is shown as a convenience.

Three columns and a separate ship are shown on the horizontal axis, which represents units of conventional distance between ship positions. All units are assumed to be the same. There are three origin points, one for the beginning of each column and the Africa, which was not in the three.

The vertical axis shows percentage of casualties per ship. For example, casualties for the Victory are plotted at 20%. A casualty is someone who was known to have been wounded, someone who was known to have been killed, or someone missing in action and presumed drowned. The percentage is the ratio of casualties to ship's complement multiplied by 100. Casualties continued over the next few weeks as enemy crews rebelled, retook their ships, and were subdued. The graph covers only the main battle on the first day.