Partition of Ireland — the division of the island of Ireland into two distinct jurisdictions, Northern Ireland and Southern Ireland, on 3 May 1921; the latter became independent in 1922 and is now the Republic of Ireland, while the former still remains in the UK

1921 battle of the Third Silesian Uprising

Centennial event in Peru

1921 battle of the Turkish War of Independence

1921 treaty which recognised that a land-locked state could register ships and sail them on the sea using its own flag

1921 treaty between Soviet Russia and Turkey

1921 South American Championship — 1921 edition of the association fotoball South American Championship

Kronstadt rebellion — uprising against the Bolsheviks in March 1921

Conflict between Panama and Costa Rica in 1921

World Chess Championship 1921

1921 short naval battle of the Russian Civil War