Complex sentence: Many of these he wrote himself, the best known being that given to the agent Violette Szabo, "The Life That I Have", which was used in the film made about Szabo, "Carve Her Name With Pride" (1958).
Split into simpler sentences: Many of these he wrote himself, the best known being that given to the agent Violette Szabo, The Life That I Have. The poem was used in the film made about Szabo, Carve Her Name With Pride (1958).