Complex sentence: At age four Hill Rise won the Man O' War Stakes on grass and the following year, after racing in the U.S. and winning the San Antonio Handicap, he was sent to race on the grass in England.
Split into simpler sentences: At age four, Hill Rise won the Man O' War Stakes on grass. The following year, after racing in the U.S. and winning the San Antonio Handicap, he was sent to race on the grass in England.