In June 1942, Brigadier General Lucian K. Truscott Jr. selected Darby to put together an elite force similar to the British commandos. The name "Rangers" derived from the force of the same name led by Major Robert Rogers during the French and Indian War. Promoted to temporary major, Darby trained his men at Achnacarry, Scotland, under the guidance of British commandos. The Rangers were seen as elite troops to be employed on hit-and-run commando raids. A charismatic person, Darby believed in leadership by example from the front. Officially, Darby commanded only the 1st Ranger Battalion, but he also trained and led the 3rd and 4th Battalions. In December 1943, Darby was promoted to colonel and given command of all three battalions.
Darby's Rangers, as his force came to be known, were first employed in combat during the ill-fated August 1942 raid on Dieppe. In November 1942, six companies performed well in Operation torch, the Allied invasion of French North Africa then under Vichy control. The companies also participated in Operation husky, the invasion of Sicily. In the invasion of Italy at Salerno, four U.S. Ranger battalions and the 41st British Commandos secured the coast at Maiori. After the destruction of the 1st and 3rd Battalions at Anzio, Darby was assigned to the Operations Division of the War Department's General Staff.
Darby returned to Italy in March 1945 and managed to secure a posting as executive officer of the 10th Mountain Division. On 30 April 1945, only a week before the end of the war in Europe, Darby was struck and killed in northern Italy by a German shell fragment. Darby was posthumously promoted to brigadier general.
Roy B. Perry III
Darby, William O. Darby's Rangers: We Led the Way. Novato, CA: Presidio, 1993.; King, Michael J. William Orlando Darby, A Military Biography. Hamden, CT: Archon Books, 1981.