It was to relieve pressure on the Soviet Union and to stop the German advances into the Middle East.
The decision to invade north Africa was made by Prime Minister Wilson Churchill and President Franklin D. Roosevelt. Operation Torch began on November 8 and finished on November 16, 1942.
As a new German offensive was coming, there were fears that the Germans would push through the Caucasus region into the Middle East and the Japanese would advance through India allowing them to link up and control Eurasia from one end to another.
Operation Torch's goal was to prevent the Axis penetration of the French dependencies in north Africa, help to secure the British line of communication through the Mediterranean and provide a potential base for future land operations in that region.