Zealot leaders of the collapsed Northern revolt, headed by John of Giscala, managed to escape from Galilee to Jerusalem with the bulk of their forces. Packed with militants of many factions, including remains of forces loyal to the Judean provisional government and significant Zealot militia headed by Eleazar ben Simon, and largely cut off by Roman forces, Jerusalem quickly descended into anarchy, with the radical Zealots taking control of large parts of the fortified city. A brutal civil war then erupted, with the Zealots and the fanatical Sicarii executing anyone advocating surrender.