Year of double-digit Epic
Rule. First two words express the number of the year of double-digit.
1918→ 18 →1 (1 letter) 8 (8 letters)
1918 O(1) declares(8) independence from Bolshevik Russia by the Ukrainian People's Republic.
O(1) pandemic(8): "Spanish 'flu".
O(1) declares(8) independence of Lithuania, Estonia, Armenia, Azerbaijan, and Georgia from the Russian Soviet Federative Socialist Republic.
O(1) adequacy(8) of the Treaty of Brest-Litovsk,
O(1) aircraft(8), Manfred von Richthofen, "The Red Baron" dies.
O(1) soldiers(8) and workers begin Kiel mutiny. W.W.Ⅰ ends.
If you try to make this, "number of letters" is on the Internet with the word "cross word".