Design criteria include rapid repair of battle damage, survivability, cost-effectiveness and off-road performance. Following the model of contemporary self-propelled howitzers, the turret assembly is located closer to the rear than in most main battle tanks. With the engine in front, this layout is intended to grant additional protection against a frontal attack, so as to absorb some of the force of incoming shells, especially for the personnel in the main hull, such as the driver. It also creates more space in the rear of the tank that allows increased storage capacity and a rear entrance to the main crew compartment allowing easy access under enemy fire. This allows the tank to be used as a platform for medical disembarkation, a forward command and control station, and an infantry fighting vehicle. The rear entrance's clamshell-style doors provide overhead protection when off- and on-loading cargo and personnel.
It was reportedly decided shortly before the beginning of the 2006 Lebanon War that the Merkava line would be discontinued within four years. However, on November 7, 2006, Haaretz reported that an Israeli General staff assessment had ruled of the Merkava Mark IV that "if properly deployed, the tank can provide its crew with better protection than in the past", and deferred the decision on discontinuing the line. On August 16, 2013, Israeli Defense MinisterMoshe Ya'alon announced the decision to resume production of the Merkava main battle tank for the IDF Armored Corps.
In 1965, Israel's military establishment began research and development on a domestically produced tank, the "Sabra" (not to be confused with the later model of the same name now in service). Initially, Britain and Israel collaborated to adapt the United Kingdom's Chieftain tank that had entered British Army service in 1966. However, in 1969, Britain decided not to sell the tank to Israel for political reasons.
By 1974, initial designs were completed and prototypes were built. After a brief set of trials, work began to retool the Tel HaShomer ordnance depot for full-time development and construction. After the new facilities were completed, the Merkava was announced to the public in the International Defense Review periodical. The first official images of the tank were then released to the American periodical Armed Forces Journal on May 4, 1977. The first Merkava Mk. 1 tanks were supplied to the IDF in April 1979, nearly nine years after the decision to produce the Merkava Mk. 1 tank was taken. The IDF officially adopted the tank in December 1979.