October 7
Balkans, Romania
German forces enter Romania on the pretext of helping to train the army of the fascist Iron Guard government. Germany's principal motive is to occupy the Ploesti oil fields.

October 9
Politics, Britain
Winston Churchill succeeds Neville Chamberlain, the former prime minister, as Conservative Party leader. Churchill was initially an unpopular figure in the party but his war leadership has gone a long way to reverse this.

October 12
Politics, Germany
Hitler postpones Operation Sealion until spring 1941.

October 15
Politics, Italy
The Italian war council decides to invade Greece. Italy plans not to tell its Axis partner Germany about the operation, which is scheduled to commence at the end of October.

October 16-19
Politics, Japan
The Dutch East Indies agrees to supply 40 percent of its oil production to Japan for six months despite British attempts to obstruct this.

October 18
Politics, Vichy France
The puppet Vichy regime introduces anti-Semitic laws.

October 28
Balkans, Greece
Italy issues an ultimatum to Greece demanding the right to occupy the country for the war's duration. Before the ultimatum expires, eight divisions, led by General Sabasiano Visconti-Prasca, attack from Albania. Italy hopes for a rapid advance to rival Germany's conquests, but mountainous terrain and the absence of maps for commanders hamper the invasion. The winter weather limits air support and thousands die of cold. Greek forces, under General Alexander Papagos, the commander-in-chief, mount stiff resistance.

October 30-31
Mediterranean, Crete
British forces occupy the Greek island.

November 5
Politics, United States
President Franklin D. Roosevelt is elected for an unprecedented third term.

Sea War, Atlantic
The German pocket battleship Admiral Scheer attacks a British convoy of 37 ships escorted by the armed merchant cruiser Jervis Bay, which fights to save the convoy. The battleship rams and sinks Jervis Bay, but only five other vessels are lost. Eastbound convoys are suspended until the 17th while the Allies search for the Admiral Scheer.