There were about two hundred European soldiers, many of them invalids

From The Great Mutiny by Christopher Hibbert. Page 177.

Wheeler was far from ready to resist attack. Two days before, he had faced the fact that mutiny at Cawnpore was inevitable, but he had still been convinced that the mutineers would make for Delhi. Now that they had turned on him instead, how could he hope to survive unless help came quickly? There were over three thousand of them, supported by the Nana's men and by most of the native population. They were well trained, well armed and well supplied, and every day there were reports of landholders from the surrounding districts coming into Cawnpore with scores of matchlock-men to reinforce the Nana's forces, whereas the numbers inside the entrenchment were less than a thousand and of these nearly four hundred were women and children. There were about two hundred European soldiers, many of them invalids; a hundred European officers from the native regiments; a hundred civilians, and a few native officers, sepoys and servants who had chosen to remain with their masters. They were at least well supplied with muskets and ammunition, there being up to ten loaded muskets available for every man capable of firing one should an assault be made on the entrenchment. There were, however, only a few light guns, most of them nine-pounders, and all of them had to be fired from positions dangerously exposed to musket-shot.