Complex sentence: Howard had planned a career as a barrister, having been called to the Bar (Inner Temple) in 1956 while fulfilling his National Service obligations in the army, during which he saw active service in the Royal Fusiliers during the Suez War.
Split into simpler sentences: Howard had planned a career as a barrister, having been called to the Bar (Inner Temple) in 1956. Meanwhile, he was fulfilling his National Service obligations in the army, during which he saw active service in the Royal Fusiliers during the Suez War.