Dresden was bombed because of it's rail lines and it's ability to resupply their troops. The Germans had to be utterly destroyed. They had to lose the very notion of waging war...and they did.
They got their comeuppance.
You can argue until you're blue in the face that the Dresden event demoralized the German people and prepared them for defeat. On the other hand all you need to do is pick up a Russian book on the matter and they'll instruct you that it was the Red Army, on the ground, using missile launchers and tanks, and lots and lots of infantrymen, who defeated the German nation and it's army.
The United States of America kept those fine gentlemen and gentleladies fully supplied with everything they needed, including Spam, to bring about that defeat.
The Brits attended the war, and the French turned out on both sides, as it were.
WWII in Europe is fundamentally an American and Russian defensive maneuver against the force of German arms and Central European industry.
And yes, the United States of America opened up a Western Front in Europe to relieve pressure on the Red Army and allow it a break-out into the North German Plain.