Essay on D-DAY/ OPERATION OVERLORD/ BATTLE OF NORMANDY

So anyways i actually have this esssay on what the most significant accomplishment of the tehran conference is: I decided that the descision of D-Day was most significant. My arguments in this essay would be that D-Day was significant in the war because :

1) It opened a second front thus pleaseing stalin/ making it easier for Russians. This made it possible for Russians to help in the war with Japan after Germany was defeted.

2) IT increased public and soldier morale...

3) IT was the turning point in the war, helped in liberation of paris.

NOW, im confused on number 2, i havent really found any solid info for morale yet....can anyone help me out? Secondly if not, can you suggest any other argument i could use instead of morale?

Thanks!