Military Affairs at Williamsport--Marching of the Maryland Regiment.
WILLIAMSPORT, Dec. 21--This morning a man named J.B. Wharton, residing at Clearspring, approached one of [the] river pickets and offered him $25 to carry dispatch to the other side. The soldier made the fact known to Col. Leonard, who had him arrested, but not until he had destroyed the dispatch. He is connected by marriage with ex-Senator Mason, now at Fort Warren.-- Col. Leonard holds him as a spy.