During the war Maryland raised 19 infantry regts, 4 cavalry regts, 1 heavy artillery regt, and 5 artillery batteries for the Union Army.
Maryland raised 2 infantry regts, 2 cavalry regts, and 4 artillery batteries for the Confederate Army.
Looks like most folks in Maryland were much in favor of remaining in the Union.
Many thousands of Maryland men went south and joined Virginia regiments. Many joined the cavalry. Maryland newspaper ran ads enticing them to go south and offered bonuses to them to do so.