1936 — , September 13

• Spain: Day 59 of 985 of the Spanish Civil War.

1937 — , September 13

• Spain: Day 424 of 985 of the Spanish Civil War.
• CBI - China: Day 69 of 2,987 of the 2nd Sino-Japanese War.
  • Day 32 of 106 of the 2nd Battle of Shanghai.
  • Day 13 of 70 of the Battle of Taiyuan.

1938 — , September 13

• Spain: Day 789 of 985 of the Spanish Civil War.
• CBI - China: Day 434 of 2,987 of the 2nd Sino-Japanese War.
  • Day 95 of 139 of the Battle of Wuhan.

1939 — , September 13

• Poland: Day 13 of 36 of Germany's Invasion of Poland. 60,000 Polish troops trapped in the Radom pocket surrender.
• CBI - China: Day 799 of 2,987 of the 2nd Sino-Japanese War.
  • Day 1 of 26 of the 1st Battle of Changsha.
• CBI - Mongolia: Day 126 of 129 of the Battle of Khalkhin Gol.

1940 — , September 13

• ETO - UK: Day 8 of 258 of the Blitz. Buckingham Palace is bombed again, wrecking the Royal Chapel.
• ETO - UK: Day 66 of 114 of the Battle of Britain.
• MTO: 150,000 strong, Italian 10th Army in Libya invades Eygpt (Operation E) going against the British Middle East Command under General Archibald Wavell and his 30,000 troops.
• East Africa: Day 96 of 537 of Italy's East African campaign in the lands south of Egypt.
• CBI - China: Day 1,165 of 2,987 of the 2nd Sino-Japanese War.
  • Day 304 of 381 of the Battle of South Guangxi.
  • Day 25 of 42 of the Hundred Regiments Offensive.

1941 — , September 13

• Russian Front: Day 84 of 167 of Germany's Operation BARBAROSSA, the overall invasion of the USSR. Germany announces that Russian POWs will get less rations than other nationalities.
  Spotlight...

  

  Russian POWs pleading for food from their German captors

  Nazi treatment of Russian POWs resulted in some 3.3 to 3.5 million deaths, about 60% of the 5.7 million captured Soviet soldiers.

  In spite of food being available, the Nazis stuck to a policy of deliberate starvation of the Russians, which lead many desperate prisoners to resort to acts of cannibalism.

  Partly in retaliation, between 374,000 and 1 million German POWs (out of an estimated 2.4 to 3.3 million) died in Soviet labor camps.
• Russian Front - Finland: Day 84 of 164 of the Battle of Hanko. The Soviets will be forced off their leased naval base.
• Russian Front - Finland: Day 10 of 28 of Finland's reconquest of East Karelia in southern Finland. The Soviets continue withdrawing from Finland back to Leningrad.
• Russian Front - Finland: Day 77 of 142 of Operation SILVER FOX, a joint German-Finnish campaign to capture the Russian port of Murmansk in the Arctic. The German troops continue withdrawing back into northern Finland.
• Russian Front - Finland: Day 75 of 140 of Operation ARCTIC FOX, a joint German-Finnish campaign against Soviet Northern Front defenses at Salla, Finland.
• Russian Front - North: Day 6 of 872 of the Siege of Leningrad.
• Russian Front - South: Day 37 of 70 of the Siege of Odessa, Ukraine.
• Russian Front - South: Day 22 of 35 of the 1st Battle of Kiev, Ukraine.
• MTO - Libya: Day 157 of 256 of the Siege of Tobruk.
• Middle East: Day 20 of 24 of the Anglo-Soviet invasion of Iran.
• East Africa: Day 461 of 537 of Italy's East African campaign in the lands south of Egypt.
• CBI - China: Day 1,530 of 2,987 of the 2nd Sino-Japanese War.
  • Day 8 of 33 of the 2nd Battle of Changsha.

1942 — , September 13

• Russian Front - North: Day 371 of 872 of the Siege of Leningrad.
• Russian Front - North: Day 132 of 658 of the Siege of the Kholm Pocket, USSR lays siege to the Kholm Pocket but the Germans hold out for a about a year and a half.
• Russian Front - Center: Day 46 of 64 of the 1st Battle of Rzhev-Sychevka, Russia. Though it will end in a stalemate, it will keep German troops from going to Stalingrad.
• Russian Front - South: Day 78 of 150 of Germany's CASE BLUE, the failed offensive to take the Caucasus oil fields.
• Russian Front - South: Day 22 of 165 of the Battle of Stalingrad, the bloodiest battle in human history. German 6th Army begin a serious offensive effort.
• MTO - Libya: US and RAF warplanes attack Tobruk and Benghazi in a joint effort with British Royal Navy. British troops reach Benghazi and Barer.
• East Africa: Day 132 of 186 of the Battle of Madagascar.
• CBI - China: Day 1,895 of 2,987 of the 2nd Sino-Japanese War.
  • Day 122 of 124 of Japan's Zhejiang-Jiangxi Campaign, launched to punish anyone suspected of aiding the Doolittle raiders in China. Roughly 250,000 Chinese will be killed.
• PTO - Alaska: Day 99 of 435 of the Battle of Kiska, Aleutian Islands. The US and Canada will defeat the Japanese invaders.
• PTO - Malaya: Day 207 of 357 of the Battle of Timor Island, a long guerrilla war ending in Japanese victory.
• PTO - New Guinea: Day 55 of 119 of the Battle of the Kokoda Track. The Australians continue pushing back the Japanese troops. This will become an Allied victory.
• PTO - Solomon Islands: Day 38 of 187 of the Battle of Guadalcanal.
• PTO - Solomon Islands: Day 2 of 3 of the Battle of Bloody Ridge on Guadalcanal.

1943 — , September 13

• Russian Front - North: Day 736 of 872 of the Siege of Leningrad.
• Russian Front - North: Day 497 of 658 of the Siege of the Kholm Pocket, USSR lays siege to the Kholm Pocket but the Germans hold out for a about a year and a half.
• Russian Front - Center: Day 38 of 57 of the 2nd Battle of Smolensk, Russia. Becomes a Soviet victory as the Axis are pushed completely away from the Moscow region.
• Russian Front - Center: Day 28 of 48 of the Battle of Bryansk, Russia. Germans continue retreating.
• Russian Front - South: Day 21 of 122 of the Battle of the Lower Dnieper River, USSR.
• MTO - Italy: Heavy German counter-attacks by six divisions around Salerno force US 5th Army back to within five miles of beaches. C-47s drop the US 82nd Airborne Division into the area. The US 9th and 12th Air Forces provide the air cover.
• MTO: The battle for supremacy in the Aegean Sea begins with an Allied raid on Rhodes.
• CBI - China: Day 2,260 of 2,987 of the 2nd Sino-Japanese War.
  • The Chinese Parliament at Kuomingtang elects General Chiang Kai-Shek as President of the Chinese Republic.
• PTO - New Guinea: Day 145 of 148 of the 2nd Battle of Lae-Salamaua. Will become an Allied victory.
• PTO - Solomon Islands: Day 30 of 56 of the Battle of Vella Lavella. The Allies will win this one.

1944 — , September 13

• ETO - France: Day 44 of 284 of the Battle of Brittany. The US 9th Army engages in heavy fighting as the German garrison keeps up its resistance at Brest, on the Brittany peninsula.
• ETO - France: Day 30 of 32 of Operation DRAGOON, the Allied invasion of southern France.
• ETO - Belgium: Day 12 of 62 of the liberation of Belgium. US troops reach the Siegfried Line after liberating several French and Belgian cities.
• ETO: US 8th Air Force: B-24s and B-17s bomb various targets in Germany.
• ETO: 8th Air Force begins Operations Frantic, while bombing targets en route, heavy bombers fly from England to Russian bases, then to US bases in Italy, and then back to the UK.
• Russian Front - South: Soviets reach the Polish-Czechoslovak border. Romania signs an Armistice with the USSR.
• MTO - Italy: Canadian forces take Coriano Ridge in the Gothic Line.
• MTO - Italy: US 12th Air Force B-25s destroy a bridge at Peschiera del Garda, cutting the Milan-Verona line. B-25s and B-26s bomb guns and defensive positions near Florence.
• MTO: US 15th Air Force: B-17s and B-24s bomb various targets in Czechoslovakia, Germany, Italy, and Poland.
• CBI - Burma: Day 166 of 302 of the Chinese Salween Offensive in Burma.
• CBI - China: Day 2,626 of 2,987 of the 2nd Sino-Japanese War.
  • Day 150 of 259 of Japan's Operation ICHI-GO.
• PTO - New Guinea: Day 274 of 597 of the Battle of New Britain.
• PTO - New Guinea: Day 145 of 481 of the Battle of Western New Guinea.

1945 — , September 13

• CBI - Burma: Japanese troops in Burma surrender.