They didn't beat France? The front lines of the war- those great trench networks stretching across northern France did not move much during the war after the initial invasion stalled- this was something Germany was keen to avoid when it came time to drawing up plans for the Second World War.

An [older post] (https://www.reddit.com/r/AskHistorians/comments/2e55o7/how_far_did_the_front_line_move_on_the_western/cjw9r12/) has a solid summary of the major battles and movements on the western front.

I guess your friend could be imaging a what if scenario wherein the war was just between France and Germany? But that's a weird thing to do since the main reason Germany dragged France into the war was because they feared France would honor their defense treaty with Russia and join the war against Germany when hostilities on the Russian border finally broke out.

Do you mean WWII? I am assuming that is a typo in the title.