Simplify the following text for a Grade 13 native English-speaking person.
Original: They issued him a colonel 's commission on May 3 , 1775 , and he immediately rode off to the west , arriving at Castleton in the disputed New Hampshire Grants ( present-day Vermont ) in time to participate with Ethan Allen and his men in the capture of Fort Ticonderoga .
Simplified: They made him a colonel on 3 May 1775 , and he immediately rode off to the west , arriving at Castleton in the disputed New Hampshire Grants ( present-day Vermont ) in time to join with Ethan Allen and his men in the capture of Fort Ticonderoga .