Mosby had to leave his children in the care of relatives, but this proved to be the first in a series of other federal government jobs and postings, many fighting rampant fraud in politically volatile situations. President McKinley appointed Mosby's daughter May the postmistress in Warrenton, which became very important after her husband Robert Campbell died in August 1889, leaving her to raise her young children alone (although her sons John Mosby Campbell and Alexander Spottswood Campbell received many letters and some money from their overseas grandfather, as to a lesser extent did Jack Russell, son of his late sister Lucie).