[2]: 88  The port, its facilities, and the rail and road links up the Rhone valley, being essential to the liberation of southern France and the ultimate defeat of German forces.

[4][5] The groundwork was laid by the Allied invasion of southern France in Operation Dragoon on 15 August by the United States Seventh Army under General Patch, with support from the French First Army who began landing on 16 August and would within days amount to two thirds of the Dragoon troops on the ground.

German defences centred on almost static infantry units guarding the coastal areas, with 11th Panzer Division providing a mobile reserve.

[2]: 112–3 Existing French Army defensive points, including large artillery batteries, provided a reasonable seaward defence.

The landward side defence was augmented with mines and the digging of weapons pits, trenches and tank obstacles.

[2]: 125 Softening up using heavy bombers to attack gun positions around Marseilles began on 12 August, the city had few anti aircraft defences.

The 23/24 attacks scored some direct hits on gun positions in the Marseille area and roaming fighter bombers took on targets of opportunity.

French artillery opened up on the fort and after two days it was clear that resistance was futile and the Marseille garrison surrendered on 27 August.

According to eye-witness accounts, in January 1943, the Germans, aided by the French police, dynamited much of the historic old town and demolished the gigantic aerial ferry or "transbordeur", an engineering tour de force that had become a major landmark of Marseille, comparable to the Eiffel Tower in Paris.

In August 1944 Hitler ordered his troops under the command of General Hans Schäfer to hold Marseille "to the last man and last cartridge" and destroy the harbour beyond repair if defeat was inevitable.

[13]: 188 A fuel pipe line was built,[13]: 191  it started at Martigues and utilising storage tanks in the La Mede refinery.

When completed it was capable of moving 450 tonnes (500 short tons) of petrol a day, which reduced the problems caused by a shortage of jerrycans and trucks.