Wentworth proposed a coup de main against San Lázaro, relying on a sudden night assault to overcome walls that artillery had not breached. Darkness was expected to prevent Cartagena's guns from supporting the fort for fear of hitting its defenders. The plan also relied on reaching lower walls, although the discussion is inconsistent about the compass direction of the intended approach. Fifty volunteers were to lead, followed by 450 grenadiers, a main body of about 1,000, and a further 500 Marines. Americans and other troops carried scaling ladders and woolpacks intended to fill trenches. The intended midnight start slipped to about 04:00 on 20 April 1741, leaving little darkness for an already difficult attack.
Notable Point · 1:56:36-2:00:10
The night assault plan and its approaching daylight deadline
Wentworth planned to storm unbreached walls under cover of darkness, but a four-hour delay consumed most of that protection.