Famous for his patriotic and historical paintings, Strain created works such as D-Day, The Monument to Divers, and Spirit of Discovery.
Early in his career, he crafted numerous western-themed oil paintings. At the beginning of the 1990s, he shifted his focus to the Civil War; later, he concentrated on a series of World War II-themed paintings.
His paintings are featured in The National Park Service's brochures.
He and his wife Nancy often participated in Civil War re-enactments.
He was influenced by the work of nineteenth-century printmaker Nathaniel Currier.