Is there an idiom that means “offering little resistance” as in a negotiation, physical fight, war?

Question

I am looking for an idiom that means "offering little resistance" in a very general way such that it can be used in the context of a negotiation, physical fight or even war. Is there such an idiom? If "offering little resistance" is too specific, try something like "being weak", which has a similar meaning.

Answer 1

You could say it was a piece of cake:

[Merriam-Webster]
: something easily done : CINCH, BREEZE

So, for example:

Fighting him was a piece of cake.