Editing MGM-51 Shillelagh (section)

==Background==
With the rapid increase in armor thickness during [[World War II]], tanks were becoming increasingly able to survive rounds fired from even the largest of World War II-era anti-tank guns. A new generation of guns, notably the British 105&nbsp;mm [[Royal Ordnance L7]], were able to cope with newer tanks, but it appeared that in another generation the guns needed would be too large to be practical.

To overcome this potential difficulty, the [[US Army]] began to favor [[high-explosive anti-tank]] (HEAT), or [[shaped charge]] rounds in the 1950s. A shaped charge's penetration is not strongly dependent on the speed of the round, allowing rounds to be fired at much lower velocities, and thus from much lighter guns. They also work better at larger diameters, and a large-diameter low-velocity gun makes for an excellent [[assault gun]] that can be mounted on light or medium-weight vehicles. However, the low speed of the round makes it hard to aim over longer distances. The US Army sought to overcome this problem by developing [[guided missile]]s that had shaped charge warheads and were accurate beyond a few hundred yards.