 Complete the following phrase:  The T-55 was the most numerous tank of the Yugoslav Peoples Army JNA. It was the mainstay of armoured combat units during the Yugoslav Wars, where it proved vulnerable to infantry equipped with anti-tank rockets and weaponry and to misemployment in urban areas as well as unfriendly terrain. But there were too many of them in service for them to be replaced entirely. During the Battle of Vukovar, where the JNA grouped a large part of its tank force, a number were destroyed, almost exclusively by infantry-carried anti-tank weapons. Serbian T-55s performed well against US M47 Patton tanks used by Croatia. The T-55 tank remained the most common tank in the armies of the various Yugoslavian successor states until recently and it was the most-used tank by all armies during the decades-long wars. T-55s were also used by Yugoslavia in 