- 6: Heavy Allied bombings of the Continent in preparation for D-Day.
- 8: D-Day for Operation Overlord set for June 6.
- 9: The German Army evacuates Sevastopol the largest city and an important port in the Crimea; the Red Army moves in.
: The Battle at the “Gustav line” near Monte Cassino continues without resolution.
- 11: The British cross the Rapido River. A “fourth” battle of Monte Cassino begins, concurrent with the opening of an offensive campaign toward Rome.
- 12: Soviet troops finalise the liberation of Crimea.
: Large numbers of Chinese troops invade northern Burma.
- 13: The bridgehead over the Rapido River is reinforced.
- 18: Battle of Monte Cassino ends with an Allied victory; Polish troops hoist their red and white flag on the ruins of Monte Cassino. The Germans have ceded it and departed.
: Allied troops take airfields at Myitkyina, Burma, an important air base; the struggle over the city itself will continue for nearly three months.
: The last Japanese resistance in the Admiralty Islands, off New Guinea comes to an end.
- 21: Increased Allied bombing of targets in France in preparation for D-Day.
- 23: Allies advance toward Rome, after a linkup of American II and III corps.
- 25: Germans are now in retreat in the Anzio area. American forces break out of the beachhead and link up with the Fifth Army; both then begin their advance on Rome.
- 27: Operation Hurricane starts. Americans land on Biak, Dutch New Guinea, a key Japanese air base; stubborn Japanese resistance until August.
- 31: The Japanese retreat from Imphal (India) with heavy losses; their invasion of India is over.