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Millennium:	2nd millennium
Centuries:	16th century 17th century 18th century
Decades:	1600s 1610s 1620s 1630s 1640s
Years:	1618 1619 1620 1621 1622 1623 1624

1621 by topic
Arts and science
Architecture Art Literature Music Science
Leaders
State leaders Colonial governors Religious leaders
Birth and death categories
Births – Deaths
Establishments and disestablishments categories
Establishments – Disestablishments
Works category
Works
v t e

1621 in various calendars
Gregorian calendar	1621 MDCXXI
Ab urbe condita	2374
Armenian calendar	1070 ԹՎ ՌՀ
Assyrian calendar	6371
Balinese saka calendar	1542–1543
Bengali calendar	1028
Berber calendar	2571
English Regnal year	18 Ja. 1 – 19 Ja. 1
Buddhist calendar	2165
Burmese calendar	983
Byzantine calendar	7129–7130
Chinese calendar	庚申年 (Metal Monkey) 4318 or 4111 — to — 辛酉年 (Metal Rooster) 4319 or 4112
Coptic calendar	1337–1338
Discordian calendar	2787
Ethiopian calendar	1613–1614
Hebrew calendar	5381–5382
Hindu calendars
- Vikram Samvat	1677–1678
- Shaka Samvat	1542–1543
- Kali Yuga	4721–4722
Holocene calendar	11621
Igbo calendar	621–622
Iranian calendar	999–1000
Islamic calendar	1030–1031
Japanese calendar	Genna 7 (元和７年)
Javanese calendar	1542–1543
Julian calendar	Gregorian minus 10 days
Korean calendar	3954
Minguo calendar	291 before ROC 民前291年
Nanakshahi calendar	153
Thai solar calendar	2163–2164
Tibetan calendar	阳金猴年 (male Iron-Monkey) 1747 or 1366 or 594 — to — 阴金鸡年 (female Iron-Rooster) 1748 or 1367 or 595

1621 (MDCXXI) was a common year starting on Friday of the Gregorian calendar and a common year starting on Monday of the Julian calendar, the 1621st year of the Common Era (CE) and Anno Domini (AD) designations, the 621st year of the 2nd millennium, the 21st year of the 17th century, and the 2nd year of the 1620s decade. As of the start of 1621, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.

Events

January 12 – Şehzade Mehmed, the 15-year old half-brother of Ottoman Sultan Osman II, is put to death by hanging on Osman's orders. Before dying, Mehmed prays aloud that Osman's reign as Sultan be ruined.
January 18 – The Dutch East India Company formally names its fortress at Jayakarta in Indonesia, calling it Batavia. Upon the independence of the Dutch East Indies as Indonesia in 1945, Batavia will be renamed Jakarta.
January 22 – The Tianqi era begins in Ming Dynasty China, six months after Zhu Changluo becomes the Taichang Emperor.
January 24 – Twelve days after the murder of Prince Mehmed on orders of Sultan Osman II, Constantinople is hit by bitter winter weather, leading to rioting by persons who believe that the punishment of Osman is the will of Allah.
January 28 – Pope Paul V (Camillo Borghese) dies at the age of 70 after 15 years as Pontiff.
January 29 – Ferdinand II, Holy Roman Emperor, declares the Elector of the Palatinate, Frederick V, to be a traitor to the Empire.
February 9 – Papal Conclave of 1621: Pope Gregory XV succeeds Pope Paul V, as the 234th pope.
February 17 – Myles Standish is appointed as the first commander of Plymouth Colony.^[1]
March 16 – Samoset, a Mohegan, visits the settlers of Plymouth Colony and greets them: "Welcome, Englishmen! My name is Samoset."
March 22 – The Pilgrims of Plymouth Colony sign a peace treaty with Massasoit of the Wampanoags.
March 31 – King Philip IV of Spain begins his 44-year rule.^[2]

April 1 – The Plymouth, Massachusetts colonists create the first treaty with native Americans.
April 5 – The Mayflower sets sail from Plymouth, on a return trip to England.
April 9 – The Twelve Years' Truce between the Dutch Republic and the Spanish Empire expires, and both sides prepare to resume the Eighty Years' War.
May 2 – The Panama earthquake affects the Isthmus of Panama, with an estimated magnitude of 6.9, and a maximum Mercalli intensity of VII.
May 12 – The city of Tornio in Lapland is founded by King Gustavus Adolphus of Sweden, becoming the northernmost city in the world at the time.^[3]
May 24 – The Protestant Union is formally dissolved.
June 3 – The Dutch West India Company is founded.^[4]
June 21 – Thirty Years' War: Twenty-seven Czech lords are executed on the Old Town Square in Prague, as a consequence of the Battle of White Mountain.
June 24 – Huguenot rebellions: Saint-Jean-d'Angély is taken, after a 26-day siege by Royal forces.

July 25 – Thirty Years' War – Battle of Neu Titschein: Remnants of the Bohemian army temporarily hold off the Imperial advance in Silesia.
August 8 – Huguenot rebellions: The French Protestant city of La Rochelle joins in the revolt by Benjamin, Duke of Soubise.
August 22 – Huguenot rebellions: Louis XIII of France besieges the city of Montauban, but is forced to abandon the battle by November 9.
September 2 – The Battle of Khotyn begins as a force of more than 120,000 Ottoman troops attacks the Moldavian city of Khotyn. Despite the Ottomans' numerical superiority, the Polish-Lithuanian Commonwealth wins the battle and forces a surrender five weeks later. ^[5]

October 9 – The Treaty of Khotyn is signed between the Ottoman Empire and the Polish–Lithuanian Commonwealth, ending the First Polish-Ottoman War.^[5]
October 9 (September 29 O.S.) – The Pilgrims of Plymouth Colony and Wampanoags celebrate a harvest feast (three days), later regarded as the First Thanksgiving, noted for the temporary peace between the English and the local Indians. The celebration is believed by later historians to have coincided with Michaelmas, observed on September 29 by the Anglican Communion on the calendar used in England at the time.
November 11 – The ship Fortune arrives at Plymouth Colony, with 35 more settlers.
December 31 – Thirty Years' War: The Peace of Nikolsburg is signed between Ferdinand II, Holy Roman Emperor and Gabor Bethlen, Prince of Transylvania. Bethlen agrees to renounce his claims to Hungary. In return Bethlen receives several counties and lands along the eastern border of the Holy Roman Empire, and Moravia is granted religious freedom.
December – The Dutch mathematician and astronomer, Willebrord Snel van Royen (1580–1626), reveals he has rediscovered the law of refraction, also known as Snellius' law.^[6]

The Venezuelan city of Petare is founded by Spanish conquistadors, as San Jose de Guanarito.
The Swedish city of Gothenburg is founded by King Gustavus Adolphus of Sweden.^[7] The king also grants city rights to Luleå, Piteå and Torneå (Tornio). Riga falls under the rule of Sweden.
Tamblot rallies an unknown, large number of people in Bohol, Captaincy General of the Philippines to revolt against the Spanish Empire.^[8]
The Dutch East India Company sends 2,000 soldiers, under the command of Jan Pieterszoon Coen, to the Banda Islands, in order to force the local inhabitants to accept the Dutch trade monopoly on the lucrative nutmeg, grown almost exclusively on those islands. The soldiers proceed to massacre most of the 15,000 indigenous inhabitants.