Captain Patchy Rat, as I recall from my very early youth, is the story of the rat who organized a swashbuckling rebellion against the tyranny of the Pied Piper of Hamelin. Illustrated. I recall an eye patch, of course, a pirates sash with rapier brandished. The book dates to 1950 era.
Have not been able to locate with desultory inquiries.
Would like to locate before all my grandchildren are too old for it.