1921 (MCMXXI) was a common year starting on Saturday of the Gregorian calendar and a common year starting on Friday of the Julian calendar, the 1921st year of the Common Era (CE) and Anno Domini (AD) designations, the 921st year of the 2nd millennium, the 21st year of the 20th century, and the 2nd year of the 1920s decade.
Classified as a destroyer tender, AD-11, the ship was delivered to the Navy on 5 December 1921 and commissioned at the New York Navy Yard the following day, 6 December 1921, Commander James H. Comfort in command. Destroyer tender, 1921–1939
- 6 December 1921
- 423 ft 9 in (129.16 m)
- 10 May 1919
- 10.5 knots (19.4 km/h; 12.1 mph)
The Mongolian Revolution of 1921 (Outer Mongolian Revolution of 1921, or People's Revolution of 1921) was a military and political event by which Mongolian revolutionaries, with the assistance of the Soviet Red Army, expelled Russian White Guards from the country, and founded the Mongolian People's Republic in 1924.
File:1921 Electricars, Ltd ad.jpg. ... 1921 Electricars, Ltd ad showing electrically powered tipper truck and Edison Accumulator trucks at ... Usage on de.wikipedia.org
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By the end of December 1921, the Finnish volunteers and Karelian Forest Guerrillas had advanced to the Kiestinki Suomussalmi – Rukajärvi – Paatene – Porajärvi lines. Meanwhile, the ca. 20 000 troops of the Red Army led by Alexander Sedyakin  have reached Karelia and mounted a counterattack.
- 6 November 1921 – 21 March 1922
- East Karelia
- Soviet victory
Leonetto Cappiello (9 April 1875 – 2 February 1942) was an Italian and French poster art designer and painter, who mainly lived and worked in Paris. He is now often called 'the father of modern advertising' because of his innovation in poster design.
The Viking invasion of Britain in 865 AD is sometimes called the Great Heathen Army, or Great Danish Army or the Great Viking Army. Previous invasions were for loot, but this one led to semi-permanent settlement.
正大集团（Charoen Pokphand Group Co., Ltd.）由泰籍华人谢氏兄弟（谢易初和谢少飞）创办于1921年，总部位于泰国 曼谷，卜蜂集团在中國大陸称作正大集团（Chia Tai Group）。
Βιογραφικά στοιχεία. Ο Ιάκωβος Καμπανέλλης γεννήθηκε στη Νάξο στις 2 Δεκεμβρίου 1921. Ήταν το έκτο από τα εννέα παιδιά του Στέφανου Καμπανέλλη, εμπειρικού φαρμακοποιού, και της Αικατερίνης Λάσκαρη.
1921 – Narodil se indický režisér Satjádžit Ráj, zemřel židovský spisovatel Josef Chajim Brenner. 1926 – Josef Skupa představil publiku loutku Hurvínka (na obrázku v sousoší se Spejblem). 1936 – Druhá italsko-etiopská válka: Císař Haile Selassie I. a jeho vláda opustili Addis Abebu.