The Imperial German Army assaulted the French with a massive artillery barrage and then advanced on French trenches using flamethrowers for the first time. Although Germany slowly advanced and captured the centre-piece of France's fortifications at Fort Douaumont they could not capture Verdun itself and their own heavy casualties meant their stated aim of "bleeding the French white" also failed.
Strategically the attack was a disaster for Germany — certainly in contrast with the other major option available to them — further advance in the East to knock the Russian Empire out of the war and capture the grain fields of Ukraine.
France's losses were appalling however. It was the perceived humanity of Marshall Petain who insisted that troops be regularly rotated in the face of such horror that helped seal his reputation — with later disastrous implications for France as a whole.
The apparent successes of the fixed fortification system (with the exception of Fort Douaumont) led to the adoption of the Maginot Line as the preferred method of defence along the Franco-German border during the inter-war years. France's army was subsequently plagued not with desertions, but rather with a general refusal to march face-first into the teeth of Germany's impregnable positions. France's troops remained in their trenches, willing to fight only in a defensive capacity.