BroadcastingM1A1 (gun barrel equipped with machine gun)M1A1 (gun barrel equipped with machine gun)The development of M1 tank originated from the MBT-70 main battle tank development plan with West Germany to replace the M60 vehicle series since the 1960s, which adopted dual hardness steel armor plus spacer structure without interlayer. Although MBT-70 was terminated due to the reduced defense budget due to the failure of the Vietnam War and the disagreement between the United States and Germany on the specifications, the defense department of Chrysler Motor Company in the United States (which was resold to General Dynamics in 1982 to become the ground system department of General Dynamics) developed the technology and specifications accumulated by MBT-70 since 1973, and the prototype XM-815 was completed in 1976, After that, 11 prototype vehicles were successively manufactured and successfully tested for 3 years; In the same year that XM815 was developed, the Yom Kippur War broke out. After receiving Soviet aid, the Middle East countries used many new personal portable anti tank weapons, such as rocket propelled grenades and anti tank missiles, which caused heavy losses to the Israeli army. These war lessons led new tanks to adopt many new equipment, including more sophisticated digital artillery shooting system and composite armor that was not widely used at that time. At this time, the number was changed to XM-11, which decided to produce 110 pilot vehicles for army evaluation in 1979, and the official service in the United States Army was in 1981.