Complex sentence: The work that he is remembered for today is a painting he did for the Red Cross during World War I in May 1918, a picture of a medic caring for a wounded soldier, signaling for help.
Split into simpler sentences: The work that he is remembered for today is a painting he did for the Red Cross during World War I in May 1918. It featured the picture of a medic caring for a wounded soldier, signaling for help.