 According to Dan Gill, geological investigations in the early 1990s confirmed earlier observations that the 114 m (375 ft) high assault ramp consisted mostly of a natural spur of bedrock.The ramp was complete in the spring of 73, after probably two to three months of siege, allowing the Romans to finally breach the wall of the fortress with a battering ram on April 16.The Romans employed the X Legion and a number of auxiliary units and Jewish prisoners of war, totaling some 15,000 (of whom an estimated 8,000 to 9,000 were fighting men), in crushing Jewish resistance at Masada.