Complex sentence: Leaving Uppingham in July 1914, Roland was awarded the Classical Postmastership at Merton College, Oxford, but when the War broke out he chose to seek a commission in the Norfolk Regiment and served with the Worcestershire Regiment in France.
Split into simpler sentences: Leaving Uppingham in July 1914, Roland was awarded the Classical Postmastership at Merton College, Oxford, but the War broke out before he took his place. He obtained a commission in the Norfolk Regiment and served with the Worcestershire Regiment in France.