They knew, when they looked at the battle plans and found out what boat numbers they were on, they knew.
Especially the ones in the first wave.
I remember watching a movie called Zulu and it had a line in it, that really does describe the situation for the average soldier getting into a boat in the first wave to hit the beaches.
Pte. Thomas Cole: Why is it us? Why us?
Colour Sergeant Bourne: Because we're here, lad. Nobody else. Just us.