In 1960, Boeing bought Vertol, a helicopter manufacturer in Philadelphia, Pa. The company had three tandem-rotor helicopters under production: the Chinook for the Army, the Sea Knight for the Navy and the Marines, and the commercial 107-II for the airlines.

The twin-turbine tandem-rotor CH-46A Sea Knight won a design competition for a medium assault transport helicopter for the Marine Corps in 1961 and made its first flight in August 1962.

The first U.S. Marine Corps Sea Knight was delivered in 1964 and began military service during the Vietnam War a year later, carrying troops and cargo to and from Navy ships in the China Sea. By 1968, the Sea Knight had flown 75,000 hours on 180,000 missions, including 8,700 missions rescuing wounded Marines, and had carried 500,000 troops.

In addition to moving troops and equipment in Marine combat assault missions, the Sea Knight was used for medical evacuation, aircraft recovery, firefighting, disaster relief and search and rescue operations. The CH-46 was phased out as the Marine Corps transitioned to the MV-22 Osprey for its medium-lift helicopter requirement.

The U.S. Marine Corps retired the CH-46 Sea Knight in August 2015.