Complex sentence: The 15th Infantry Regiment shipped out from the New York Port of Embarkation on December 27,1917, and joined its brigade upon arrival in France, but the unit was relegated to labor service duties instead of combat training.
Split into simpler sentences: The 15th Infantry Regiment shipped out from the New York Port of Embarkation on December 27,1917, and joined its brigade upon arrival in France. The unit was relegated to labor service duties instead of combat training.