At the time it was chosen for Gemini duty, the Titan II was the most powerful rocket in America's inventory. An improved version of the Air Force's Titan I, it first flew successfully in March 1962.

NASA flew a total of 12 Gemini missions, 10 of which had crews ... of the U.S. Air Force's intercontinental ballistic missile Titan II. Known as the Titan II GLV, this rocket had never flown ...