Technically his amateur efforts were against regulations because soldiers were not meant to have cameras in their kit. But Mawley ignored the instruction and picked up a "Soldier's Kodak" before he sailed.
Kodak called its handy unit the Vest Pocket Autographic. A New Zealand advertisement from the time encouraged departing troops to "take a Soldier's Kodak with you and bring back your own priceless picture record of the great war".
Mawley was 29 when he enlisted in September 1915. He had been active in the Masterton Citizens' Defence Corps, and was quickly promoted to sergeant. His journey to the Western Front can be traced in images he took during a stopover in Egypt. These show the pyramids and soldiers on camels.
In September 1916 the Rifle Brigade officer suffered head wounds and returned to Britain from France for treatment. A piece of high explosive shell tore through the left side of his face.
Recovering at Brockenhurst Hospital near Southampton, Mawley lobbied for his wife Elsa to join him in England, which appeared to have unsettled the military brass.
Mawley's file shows Defence Force commanders agreed, but made the injured officer pay the cost of a coded telegram sent to London advising of Elsa's arrival at Plymouth on board the troopship Rotorua.
The bill, for 1 10s 5p, was sent to Mawley's lawyers. A senior military commander noted on the file that "no encouragement should be given to wives to go to England. There may be difficulties in food supplies."
Lieutenant Mawley spent some time recuperating from his facial wounds, and was posted to Sling Camp, where he helped train successive drafts of New Zealanders who rotated through the Salisbury Plains barracks before crossing the channel for Europe.
In August 1917, he was considered fit for active service and returned to France.
Two months later, on October 12, Mawley was cut down by machine-gun fire during the advance on Passchendaele while at the head of his men - one of 45 officers and 800 men who perished on that catastrophic day.
Mawley's WWI photographs can be found on the National Army Museum website nam.recollect.co.nz
100 Kiwi Stories runs Monday and Thursday.