The Titan I was the United States' first true multistage ICBM. The program began in January 1955 and took shape in parallel with the Atlas (SM-65/HGM-25) intercontinental ballistic missile (ICBM). The Air Force's goal in launching the Titan program was twofold: one, to serve as a backup should Atlas fail; and two, to develop a large, two-stage missile with a longer range and bigger payload that also could serve as a booster for space flights. Produced by the Glenn L. Martin Company, Titan I was a two-stage, liquid-fueled, rocket-powered missile. Like Atlas, it had a liquid cryogenic fuel system, which was a severe drawback. The first stage delivered 300,000 pounds of thrust; the second stage 80,000 pounds. The missile utilizes both radio and all-inertial guidance. Deployed in a "hard" silo, it had to be raised to surface by a special launcher for firing. The Titan I had an effective range of 5,500 nautical miles. As each stage was fired, its engines and fuel tanks dropped away, thereby decreasing the weight and mass of the vehicle. That made for a more efficient missile, which resulted in increased range and a larger payload.
When the storable fueled Titan II and the solid fueled Minuteman I were deployed in 1963, the Titan I and Atlas missiles became obsolete. They were retired from service as ICBM's in early 1965.