1) AA Milne served in it 2) AEF conflict 3) Armistice Day conflict 4) Event from 1914-1918 5) Initialism since 1939 6) It ended in 1918 7) It ended November 11, 1918 8) It ended on November 11 9) Modern European history subj 10) Old european conflict 11) Over There subj 12) Over There was inspired by it Found on https://www.crosswordclues.com/clue/wwi