Mervyn volunteered for enlistment in January 1915. At the time he was married and working as a senior linesman, possibly for the Hydro Electric Commission. He was allotted to the 4th reinforcements for the 12th Battalion and served on Gallipoli arriving there in May 1915 when the weather was recorded as being uncomfortably hot and the flies particularly troublesome. Water shortages at this time also added to the men’s discomfort, allowed just over 2 litres of water per day for all purposes.
In August as the number of men evacuated for illness outnumbered the wounded, Mervyn Rowbottom was among the casualties suffering with diarrhoea, influenza and debility. He did not return to Gallipoli, instead remaining in Egypt for treatment and then undertaking guard duties as he battled rheumatism.
On 6 March 1917 he was transferred to the Australian Imperial Camel Corps and posted to the 3rd Battalion. After several more admissions to hospital for kidney trouble and then diabetes, the decision was made that he should return to Australia.
Mervyn Rowbottom, now aged 50 years and a widower, once again volunteered for service in 1940. He had previously been rejected, but tried again and was accepted and posted to Area Headquarters. He was discharged on 22 September 1944, now aged 56 and suffering from some of the same conditions as in WW1.