I believe most of them realized that by 1945, but you always had the die-hards. I have seen videos of German officers giving the Nazi salute to truckloads of prisoners AFTER the war ended.
A guy I worked with back in the 50s was stationed in Germany in '46 and was dating a local girl. While waiting for her and talking with her old man, the son comes down the stairs, and not seeing the soldier there, gave the old man the Nazi salute and said "Good evening, father." The old man nearly had a stroke and the kid almost wet his pants. Stupidity takes a long time to die out.
I think each branch saw the writing on the wall in their own way; for the army it was Stalingrad, for the air force it was seeing fighters escort bombers all the way to the target, and for the navy it was when the U-boats attacked convoys which in turn launched their own planes.
These developments probably convinced the generals to kill Hitler.