Complex sentence: During the First World War, he enlisted in May 1917 and served with the American Expeditionary Forces from October 1917 to July 1919; was decorated with the Distinguished Service Cross, Distinguished Service Medal, Purple Heart, and the French Croix de Guerre with Palm.
Split into simpler sentences: During the First World War, he enlisted in May 1917 and served with the American Expeditionary Forces from October 1917 to July 1919. He was decorated with the Distinguished Service Cross, Distinguished Service Medal, Purple Heart, and the French Croix de Guerre with Palm.