Despite this first failure, Commune leaders were still convinced that, as at Montmartre, French army soldiers would refuse to fire on national guardsmen. They prepared a massive offensive of 27,000 national guardsmen who would advance in three columns. They were expected to converge at the end of 24 hours at the gates of the Palace of Versailles. They advanced on the morning of 3 April—without cavalry to protect the flanks, without artillery, without stores of food and ammunition, and without ambulances—confident of rapid success. They passed by the line of forts outside the city, believing them to be occupied by national guardsmen. In fact the army had re-occupied the abandoned forts on 28 March. The National Guard soon came under heavy artillery and rifle fire; they broke ranks and fled back to Paris. Once again national guardsmen captured with weapons were routinely shot by army units.