Complex sentence: In April 1917, she married Sir Christopher Bullock, whom she had met at Cambridge; he was a powerful civil servant at the British Air Ministry, rising to Permanent Under-Secretary from 1931 to 1936.
Split into simpler sentences: In April 1917, she married Sir Christopher Bullock, whom she had met at Cambridge; he was a powerful civil servant at the British Air Ministry. Bullock rose to become the Air Ministry's Permanent Under-Secretary from 1931 to 1936.