What do you think the other leaders hoped to accomplish by giving in to Hitler

They didn't necessarily give into them, they were forced to (not necessarily either, just hear me out) ...

It's either they keep fighting and more men and women (sometimes) are lost or they should just surrender.

In a way, you could assume they hoped to accomplish a chance to live?

To try and remain in peace because it had only been 20 years since the first world war and most of Europe was still in ruins