remember that there was already a first front in Britain and the Atlantic then there was another one in Africa and then Italy.
More jokes.
1) Britain was never invaded. The Battle of Britain, was fought entirely in the air, and lasted approx. three months from July to Oct. of 1940. Props to the British Air Force for being able to establish eventual air superiority.
2) The Battle of the Atlantic involved several hundred submarines, and maybe several thousand merchant ships and government owned cargo carriers. The total losses are tallied in the tens of thousands. In other words, approximately a week of Stalingrad fighting.
3) The North African Campaign was an absolute sideshow next to what was happening on the Eastern Front. Once again, total casualties are tallied only in the tens of thousands. Many more were captured, but that is because Hitler and Mussolini had no means of shipping those men back to the Continent. Soldiers who were transferred from North Africa to the Eastern Front, would complain that it was like entering hell (btw the soldiers transferred from France and the Low Countries complained about the same thing).
Bottom line - the scale, brutality, and amount of armament involved - puts the Eastern Front on an entirely different level than any other theater of the war. The Eastern Front of WW2 is the most brutal fighting experienced in the history of our species. Meanwhile, the battles in the West, in Africa, in Asia, could have easily happened in WW1 or in the 19th century in terms of the losses involved.
Britain and France both lost much more men in WW1 than in WW2, though that war is rarely ever discussed when fighting for bragging rights over the dead.
Britain - WW1 losses: 887K military deaths
Britain - WW2 losses: 383K military deaths
France - WW1 losses: 1.4M military deaths
France - WW2 losses: 217k military deaths.