Partly it's because he painted subjects like the Holocaust and nuclear war.
Initially he painted traditional subjects about the sea and life on the seas.
He painted historical subjects, and his works are held in considerable estimation.
He painted history, landscape, and portrait subjects with much success.
He also began painting marine subjects for which he became known.
He first began painting military subjects for his own interest in 1968, turning professional when he left the army.
But Sargent painted other subjects, too, not least among them children.
He painted historical, classical and religious subjects in the academic style.
He also painted portraits, religious subjects, still life, and local scenery.
He usually painted interiors and familiar subjects of general interest.