On 23 May 1944, at 0600 hours, the 2nd Canadian Infantry Brigade, Princess Patricia’s Canadian Light Infantry right and the Seaforth Highlanders left, assaulted the Adolf Hilter Line with the 3rd Field Company in support. The unit's war diary describes the day well.
Reveille sounded at 0400 hours and the sapper detachments were soon on their way to join their infantry battalions. The barrage opened at 0500 hours and the leading infantry companies set off at 0600 hours with sappers in close support. All went well until 0740 hours when a minefield was reported in the PPCLI area. The platoon commander, Lieutenant Carr-Harris, had lost touch with both the engineer and infantry headquarters. Sergeant Kerr was sent forward with a party of sappers to deal with the delay but was pinned down by enemy fire, losing three sappers. As it turned out, Carr-Harris was already in the thick of it. He had taken his men with him as soon as the tanks encountered the minefield and the anti-tank guns covering it from a distance. Under pressing pressure from artillery and directed machine-gun fire, the sappers were able to find a way through the minefield. Lieutenant Carr-Harris, Lance Sergeant Irvine and Acting Corporal Harrison were all decorated for bravery that day. The hell the sappers suffered that day on the Hitler Line saw the worst carnage of the Italian Campaign. By the end of the day the Hitler Line was smashed and the 5th Armoured Division started moving forward to seize a crossing on the Melfa River to open the Road to Rome. The 3rd Field Company had lost five killed and 13 wounded or missing.
On the 23rd May 1944, 2 Canadian Infantry Brigade, supported by the North Irish Horse, Royal Armoured Corps, attacked the Adolph Hitler Line between Acquino and Pontecorvo. Lance-Sergeant Irvine was detailed to a mine sweeping party moving forward with the leading battalion, the Princess Patricia's Canadian Light Infantry. At 0740 hours the tanks of the North Irish Horse encountered mines in the area [Map Reference 74719, 6] and were unable to advance.
The Engineer Non-Commissioned Officer moved forward with the mine sweeping party led by Lieutenant Carr-Harris and in spite of intense fire assisted in the organization and conduct of the detail. While proceeding with his task, Lance-Sergeant Irvine was wounded in several places by shrapnel. In spite of these wounds this Non-Commissioned Officer continued to direct the party for several minutes until unable to proceed any further. His determination and devotion to duty inspired the entire party and was no doubt a major contribution to the final accomplishment of the task.