Monk defended the parliament--Lambert attacked it.

Monk had no more inclination to support parliament than Lambert, but he had it inscribed on his standards, so that all those of the contrary party were reduced to write upon theirs, "Rebellion," which sounded ill to puritan ears.

They flocked, then, from Lambert to Monk, as sinners flock from Baal to God.
Monk made his calculations; at a thousand desertions a day Lambert had men enough to last twenty days; but there is in sinking things such a growth of weight and swiftness, which combine with each other, that a hundred left the first day, five hundred the second, a thousand the third.

Monk thought he had obtained his rate.

But from one thousand the deserters increased to two thousand, then to four thousand, and, a week after, Lambert, perceiving that he had no longer the possibility of accepting battle, if it were offered to him, took the wise resolution of decamping during the night, returning to London, and being beforehand with Monk in constructing a power with the wreck of the military party.
But Monk, free and without uneasiness, marched towards London as a conqueror, augmenting his army with all the floating parties on the way.