As a young Salvation Army officer, Arthur had also applied to go as a chaplain to the Great War. However, his commanding officer, Commissioner Hay, had been afraid to appoint him, as — knowing McIlveen's willingness to go into danger — Hay feared "he would not see the war out for an hour before being shot down".

One of the more unusual acts of Mac's pre-WWII ministry was to campaign successfully against a women's wrestling match in Broken Hill, NSW, which he saw as an assault against the dignity of womanhood. As a result of his protests the bout was cancelled.
During the Second World War, with the Rats of Tobruk, Brigadier Arthur McIlveen came into his own. Along with several other brave Salvationists — men serving as chaplains and Red Shield representatives — McIlveen defied imminent death to "be Jesus" to the men he served.
The ‘Rats of Tobruk’ remembered Mac's kindness and compassion and, years later, raised the money to buy a cottage in which Mac lived in retirement. The Rats of Queensland wrote to Mac that, "You had so little to give yet your constant smile, faith in victory, courage and complete disregard of your own comfort at all times, your humility, self-effacement and driving force took you far beyond the call of extraordinary duty."
McIlveen was promoted to Glory in 1979.