During which war was the US Army Ranger school established?

The establishment of the US Army Ranger School occurred during World War II. The school was first opened in 1943 as a response to the needs of the military for specialized troops capable of conducting light infantry operations in various theaters of war. The training program was designed to develop the skills required for leadership and effectiveness in combat situations that Rangers might encounter.

While there were significant military developments and other elite units formed during the Korean War, Vietnam War, and Gulf War, these conflicts did not coincide with the founding of the Ranger School. Instead, the legacy and expertise developed during World War II set the groundwork for future operations, including those in Korea, Vietnam, and beyond. Therefore, the correct answer reflects the historical context of when the Ranger School was created and the evolution of special operations forces.