Complex sentence: Manion entered the House of Commons through a by-election in 1938 and campaigned against conscription despite the fact that he had joined the Unionists in 1917 because he favoured the draft.
Split into simpler sentences: Manion entered the House of Commons through a by-election in 1938. He subsequently campaigned against conscription despite the fact that he had joined the Unionists in 1917 because he favoured the draft.