The chronology is primarily one of tactical events of World War II from the time the United States was drawn into the conflict on 7 December 1941 until the surrender of Japan in 1945, with emphasis on ground action by United States armed forces. Air and naval co-operation, combat actions of foreign units-both Allied and enemy-and general events of world-wide interest arc detailed within the scope of space limitations. Geographically, events for the period from Pearl Harbor to the invasion of Normandy on 6 June 1944 are arranged in sequence from the Western Hemisphere westward around the world. From D-Day to the end of the war the order is reversed, the action in western Europe taking precedence. The dates used are those of the area under discussion. Thus, the attack on Pearl Harbor is dated 7 December while the events occurring simultaneously in the Far East appear under 8 December. An exception has been made for the Gilberts and Marshalls campaign because the scene of engagement lies so near the International Date Line and also because most of the records consulted are dated west longitude. To itemize the materials used in the preparation of this work of reference would be tedious, if not impossible. Suffice it to say that the compiler consulted extensively After Action Reports, histories of units engaged, dispatches of the Allied commanders, and other primary sources, but for correctness and completeness relied heavily on the findings of the historians who have written and are writing other volumes for the UNITED STATES ARMY IN WORLD WAR II, on the History of United States Naval Operations in World War II by Samuel Eliot Morison, and on The Army Air Forces in World War II edited by Wesley Frank Craven and James Lea Cate.