Christopher Dunn was the son of Robert Horatio and Mary Sophia Louisa Dunn of Kaitaia, New Zealand. Grandson of Rev Joseph Matthews, a pioneer missionary in Kaitaia.

Dunn married Mary Geddes in 1906. They had two sons, Christopher Francis and Robert James. Mary died only hours after giving birth to Robert. He married Sarah Shepherd in 1910. They had two daughters, Vivienne Maud and Elsa Rose.

Dunn's nephew, Kenneth Gordon Dunn (414605), was killed in a flying accident in the U.K. while serving with the RNZAF in the Second World War.

Dunn arrived in South Africa in time to see a bit of the countryside and be present at the signing of the peace treaty, but did not actually see any action.

At the time Dunn enlisted with the New Zealand Expeditionary Force (NZEF) in 1915, he was legally separated from Sarah.

Within a fortnight of arriving in Egypt, Dunn and the rest of the 4th Reinforcements to the NZEF were at Gallipoli. Dunn was involved in the attack on Chunuk Bair, where he was wounded. Fortunately he was able to make it back down to the beach, where he was put on a hospital ship bound for Egypt.

After recovering from his wounds, he rejoined his unit on the island of Lemnos. He was hospitalised there and so did not return to Gallipoli with them. After the evacuation from Gallipoli, he returned to Egypt, where he was assigned to the 1 New Zealand Infantry Training Battalion. He remained in Egypt while the rest of the New Zealand Division headed for Western Europe. Dunn returned to New Zealand 2 months later, having been declared unfit for duty.

Two days before leaving for home, Dunn forfeited 8 days' pay after being caught with a forged leave pass on 9 June 1916.

After returning to New Zealand, Dunn was awarded a 50-acre farm block at Herekino.

Listed at Archives New Zealand as DUNN, Christopher Blencoe Noble AWMM