On 5 March 1913, he married Margarette Ann Florence Johnson at St John's Church, Wellington. She was the daughter of Captain Johnson, the harbour master; John Mason was best man. When New Zealand declared war against Germany in 1914, Oram sold his law practice and joined the army. He was declared unfit for overseas service and served first in Palmerston North, and then at Base Records in Wellington, where he attained the rank of Captain. He was awarded an MBE (military) in 1919.