Time was of the essence and the men climbed the walls as fast as they could while being as silent as they could.
This was because these men were currently in their most vulnerable position and were thus eager to get up on that wall as soon as possible before the clinking and clanking of the metal hooks against the stone walls could somehow wake the guards up.
And, so they scampered up the walls in what to them felt like hours but in actuality was less than half a minute until all ten men were up on the ramparts.
As soon as their feet hit the stone floor, these men equipped their crossbows and quickly swiveled their heads looking for any guards.
Alexander had wanted these men to carry the 'Instant bow' so that each of the men would have five rapid shots but found that the large bow was too hard to climb up with.