One of Moras' most trusted lieutenants was to command them while, after some discussion, it was arranged that Herrara should be in general command of the garrison.
The brave fellow was reluctant to remain inactive; but he had been, for some time, seriously unwell, having been laid up for a time with a severe attack of dysentery; and was really unfit for any continued exertion, although he had made light of his illness, and refused to go on the sick list.

Terence pointed out to him that the command was a very important one.

Here all the plunder that they might obtain from the enemy would be carried; and if, by means of spies or traitors, the French obtained news of the situation of the post, he might be attacked in great force before the other detachments could arrive to his assistance.
As there were four thousand French troops at Zamora, it was agreed that no direct attack could be made upon the town.

Bull with his force was to watch the garrison, attack any detachments that might be sent out--leaving them severely alone when they sallied out in force, and to content himself with outmarching their infantry, and beating off any cavalry attacks.

He was, if necessary, to retreat in the direction of their stronghold.
Macwitty was to occupy the road between Zamora and Valladolid, while the main body held the roads between both the latter town, and Zamora, to Salamanca.