After the Fall of France, he led the Maquis des Glières, organizing attacks and parachute drops, and was the recipient of multiple military awards including the Croix de Guerre.

In September 1939, while his battalion left for the Eastern front, the section commanded by Morel (who had been promoted to lieutenant) remained guarding the Italian border.

After the Italians entered the war on 12 June 1940, he distinguished himself in the battle of the Alps, decisively exploiting the success of one of his patrols to take five prisoners and seize important supplies.

After the invasion of the zone libre by the Germans in November 1942, Tom Morel went underground, and joined the resistance in Haute-Savoie where he found his old commander, Vallette d'Osia, organizer and head of the Armée Secrète (AS) for that department.

He signed up, along with Vallette d'Osia's old adjutant Captain Maurice Anjot, to organise the AS, whose numbers were multiplying after the February 1943 initiation of the STO, the scheme of obligatory labour in Germany.

Romans-Petit appointed Morel head of the Maquis in the department, and gave him the task of organizing the receipt of allied parachute drops on the Glières Plateau.

In February and March, numerous clashes occurred with the Groupe mobile de réserve (GMR) and with the Milice of the Vichy régime who were surrounding the plateau.

They had to provide currency in exchange for Michel Fournier, medical student and auxiliary doctor for the maquis, who had been arrested at le Grand-Bornand several days earlier.

On 2 May, his body was brought down to the valley, and he remains buried today in the Morette military cemetery, now the Glières en Haute-Savoie national necropolis.

As an instructor at Saint-Cyr in 1942, he pointed his pupils towards the Resistance, and threw himself body and soul into the struggle against the invader, acting in turn as an acquirer of supplies, information agent and propagandist.

On 9 March 1944, having taken the village of Entremont by assault, he was casually assassinated during an negotiation which he had asked from his conquered foes in order to spare the pointless shedding of French blood.

But it was also with an ideal of generosity and sacrifice, which was the conscious and desired fruit of his faith: "Pray", he said to the priest who was his confidant, "that I will keep to the end, in the midst of difficulties just as among the happiness and joys of family, this soul, which rejects mediocrity and which always wants to raise itself into nobility".