Private Samuel McLain was a musician in the 144th Ohio National Guard. In a letter to his wife, he narrates the days leading up to the Battle of Monocacy, the progress of the Battle on July 9, and the retreat of Union forces:

July 7 [1864]: We left Camp Parole at 2 o'clock. We arrived near Harpers Ferry [Monocacy Junction] at 12 o'clock... I think the Rebs will not fight.

July 8: We can hear the battle [west of Frederick, Maryland]. We started after Johnny Rebs after midnight.

July 9: 2 o'clock. The battle is raging fiercely. 4 o'clock. The Rebs are driving our men, oh my God we have to retreat. We are striking for Baltimore. Our men are getting all cut to pieces. The artillery has left. I must go. Every man must save themselves. We have 45 miles to retreat.

July 11: We arrived in Baltimore or part of us ... We march all night and until 2 o'clock the next day. We have had a hard march. My feet are all raw ... I am well but sore feet ... We had to [throw] all our baggage away and guns. I stuck to my drum and grub. We got no sleep for three nights.