Clifford Joseph O'Brien was born in Bathurst, NB, the son of Mr and Mrs William O’Brien. He had two brothers and four sisters.
When he enrolled, he declared his trade as a hard rock miner having worked as such in Kapuskasing, ON. He also had logging and construction experience. At the time of his enlistment, he had been working in the Spruce Falls Pulp & Paper Mill in Cavascacy, ON when he traveled to Picton, ON and joined the Hastings & Prince Edward Regiment on 29 June 1940. He was sent the Infantry Training Centre in Camp Borden and overseas as a reinforcement in February 1941. He transferred to the Royal Canadian Engineers in October 1941.
Sapper O’Brien was first posted to Number 2 Canadian Road Construction Company and later to the 1st Field Squadron in June 1943. Over the next five months, Clifford learned basic sapper skills over the many training camps and bridging exercises the Squadron squeezed in before their planned deployment to Italy. Although he was fully qualified as a Pioneer 'C' (combat engineer in today's parlance), he was qualified as a Tinsmith Group ‘B’ for pay purposes.
As part of the 5th Canadian Armoured Division, the 1st Field Squadron sailed for Italy later in the year and landed in Naples on 8 November. Once ashore in Italy, the Squadron took over well-used equipment and vehicles from the British 7th Armoured Division who were returning to England. The Squadron was moved over 200 miles southeast to the Taranto area and attached the 1st New Zealand Division. Despite having to complete a great deal of vehicle and equipment maintenance, they immediately got to work on bridging and route repair and construction tasks. As the 5th Armoured Division gained strength in Italy, the Squadron moved closer and closer to the front relieving other Eighth Army formations. The Squadron then moved back towards Naples to the city of Caserta. Again, bridging and mine training, rest and maintenance, as well as planning for the Liri Valley operation occupied their time. In mid-May, the 5th Armoured Division started moving forward to the Hitler Line.
The Squadron had been moving up behind the 1st Canadian Division ready to exploit through the Hitler Line. On 21 May, they were in the Portocorvo area where they waited to follow up the 10th Field Squadron fighting to cross the Melfa River. While some sappers were working on improving the approaches to the OXFORD Bridge, most were in the harbour. There was heavy shelling on 23 May. Sapper O’Brien was killed and five others including Sapper Wylie were wounded. Sapper Clifford Joseph O'Brien is buried in the Cassino Commonwealth War Cemetery. He was 35 years old.