Complex sentence: The Fifty-third marched to Falmouth where it arrived on November 19th and performed provost guard duty until December 11, when it left quarters and took up a position opposite Fredericksburg in support of Union batteries engaged in the sad bombardment of the town.
Split into simpler sentences: The Fifty-third marched to Falmouth where it arrived on November 19th and performed provost guard duty until December 11th. Tt then took up a position opposite Fredericksburg in support of Union batteries engaged in the bombardment of the town.