“Despite’s Mosby opposition to secession, he nevertheless enlisted in the Confederate Army in 1861 out of loyalty to friends and family in his home of Virginia.”
That sentiment was shared by Robert E. Lee and basically by the 92% of the total number of Southerners who did not own slaves. But Lincoln sent an invading army into their homeland; they did not have much choice at the time.
Long before the war the northern states had invaded the south by controlling the Congress that made laws harming the south. They felt invaded long before 1865.