Organized in February 1961 as a Strategic Air Command (SAC) SM-68 Titan I intercontinental ballistic missile launch squadron.
 On 1 April 1961, SAC placed the 851st Strategic Missile Squadron on operational status.
 In September 1962, the 851st became the last Titan I Squadron to achieve alert status.
 The squadron's missiles were deployed in a 3x3 configuration, which meant a total of nine missiles were divided into three sites.
Each missile site had three ICBM missiles.
 Missiles were installed in the silos between 28 February and 20 April 1962.
 The missile sites were:
851-A, 2 miles ESE of Lincoln, California        38°52′54″N 121°15′56″W
851-B, 4 miles NNE of Sutter Buttes, California  39°16′32″N 121°49′46″W
851-C, 6 miles N of Chico, California            39°49′05″N 121°51′10″W
On 24 May 1962, during a contractor checkout, a blast rocked launcher 1 at complex 4C at Chico (851-C), destroying a Titan I and causing heavy damage to the silo.
After the investigation, the Air Force concluded that the two separate explosions occurred because of a blocked vent and blocked valve.
After damages were repaired, the Chico complex became operational again on 9 March 1963.

In November 1962, two months after the squadron became fully operational, SAC subjected the unit to an operational readiness inspection.
The 851st became the first Titan I unit to pass.

On 19 November 1964, Defense Secretary Robert S. McNamara announced the phase-out of remaining first-generation Titan I missiles by the end of June 1965.
 Consequently, the Titan Is of the 851st were removed from alert status on 4 January 1965.
The last missile was shipped out on 10 February.
 The Air Force subsequently inactivated the squadron on 25 March.
Organized in February 1961 as a Strategic Air Command (SAC) SM-68 Titan I intercontinental ballistic missile launch squadron.  On 1 April 1961, SAC placed the 851st Strategic Missile Squadron on operational status.  In September 1962, the 851st became the last Titan I Squadron to achieve alert status.  The squadron's missiles were deployed in a 3x3 configuration, which meant a total of nine missiles were divided into three sites. Each missile site had three ICBM missiles.  Missiles were installed in the silos between 28 February and 20 April 1962.  The missile sites were:
851-A, 2 miles ESE of Lincoln, California        38°52′54″N 121°15′56″W
851-B, 4 miles NNE of Sutter Buttes, California  39°16′32″N 121°49′46″W
851-C, 6 miles N of Chico, California            39°49′05″N 121°51′10″W
On 24 May 1962, during a contractor checkout, a blast rocked launcher 1 at complex 4C at Chico (851-C), destroying a Titan I and causing heavy damage to the silo. After the investigation, the Air Force concluded that the two separate explosions occurred because of a blocked vent and blocked valve. After damages were repaired, the Chico complex became operational again on 9 March 1963.
In November 1962, two months after the squadron became fully operational, SAC subjected the unit to an operational readiness inspection. The 851st became the first Titan I unit to pass.
On 19 November 1964, Defense Secretary Robert S. McNamara announced the phase-out of remaining first-generation Titan I missiles by the end of June 1965.  Consequently, the Titan Is of the 851st were removed from alert status on 4 January 1965. The last missile was shipped out on 10 February.  The Air Force subsequently inactivated the squadron on 25 March.
851st Strategic Missile Squadron