Franck was called up to the Royal Navy in 1943 and assigned to serve on a Arromanches Merchant Navy ship. This was an Estonian cargo ship in Hull, armed with two 20mm anti-aircraft guns and an old 12 pounder. They sailed in a 6-knot convoy to Canada which took eleven days. On arrival in Canada they experienced great hospitality before sailing back to Belfast.

He was then transferred to an ex-Danish vessel based in Cardiff that was being modified to carry troops and ammunition for the Normandy invasion. It was partly crewed by Puerto Rico stevedores serving in the US armed forces. The US infantry on board impressed Franck with their fatalistic defiance, their attitude being that they were not coming back and they just had to seize their objectives on the beach whatever the cost. On arrival at Omaha beach they began to ferry troops and ammunition ashore, using DUKW amphibians. Only one of these vehicles returned to the ship. From his vantage point on board Franck could see the course of the assault and observed how the US troops persisted in the attack, despite taking heavy casualties as they disembarked. In Mumbai on his next posting they got news of the dropping of the Atom bomb to end the war and celebrated with free beer.

At the time, as a young man, the whole thing seemed like a big adventure. Looking back on these events he recalls the waste of life and the single-mindedness of the American troops.