Complex sentence: He developed his theory during World War I, depositing his claim to priority in a sealed document at the British Museum in 1918 and then in 1920, published his work, whose short title is "Shakespeare Identified", through Cecil Palmer in London.
Split into simpler sentences: He developed his theory during World War I, depositing his claim to priority in a sealed document at the British Museum in 1918. In 1920 he published his work, whose short title is "Shakespeare Identified", through Cecil Palmer in London.