Complex sentence: On January 31,1917, Pratt left El Paso to rejoin his original regiment, the 4th Cavalry, at Schofield Barracks, Hawaii, arriving in March.
Split into simpler sentences: On January 31,1917, Pratt left El Paso to rejoin his original regiment. He arrived at the 4th Cavalry, at Schofield Barracks, Hawaii, in March.