| 1941 | |
| December 7 | Japanese attack Pearl Harbor. US declares war on Japan. |
| December 8 | Japanese assault Philippines, Hong Kong, Malaya, and Wake Island. |
| December 11 | Germany and Italy declare war on the United States. |
| 1942 | |
| February 15 | Singapore falls to General Yamashita. |
| March 12 | General MacArthur leaves Philippines vowing “I shall return.” |
| May 6 | All US forces in Philippines surrender. |
| May 7 | Battle of the Coral Sea – first Japanese setback of the war. |
| June 4–7 | Battle of Midway – Japanese lose four carriers; turning point of the Pacific War. |
| August 7 | US Marines land on Guadalcanal in Solomon Islands. |
| 1943 | |
| February 1 | All Japanese troops evacuate Guadalcanal. |
| June 30 | Operation Cartwheel – operations against remainder of Solomon Islands. |
| November 20–23 | Battle of Tarawa – start of Marines’ “island hopping” operations. |
| 1944 | |
| February 2 | Marines assault Kwajalein in Marshall Islands. |
| June 11 | US Task Force 58 bombards Mariana Islands. |
| June 15 | Invasion of Marianas begins at Saipan. |
| June 19 | Battle of the Philippine Sea – destruction of Japanese naval air power. |
| August 8 | Island of Guam in Marianas occupied. |
| September 15 | 1st Marine Division (MarDiv) assaults Peleliu in Palau Islands. |
| October 20 | US Army under MacArthur lands on Leyte in Philippines. |
| November 27 | B29 Superfortress bombers firebomb Tokyo. |
| 1945 | |
| February 19 | Three Marine divisions assault Iwo Jima. |
| March 26–June 30 | Battle of Okinawa. |
| August 6 | Atomic bomb dropped on Hiroshima. |
| September 2 | Japanese surrender aboard USS Missouri in Tokyo Bay. |
Area under Japanese control, end of September 1944 (approx). In 1941/42 Japan had established a defensive perimeter throughout the Pacific and Southeast Asia, hoping to force the United States to the negotiating table rather than engage in a long, drawn-out conflict. By the end of 1944, however, that perimeter was already in the process of collapsing.