Do to

[Pooh]

"He did a lot of harm to the cause."

Please tell me what this mean?
Is this some kind of idiom?

[Cerberus™]

What is the context? To do harm to x means to do something bad to it. A cause can be a goal.

[Mouhanaad]

it is meaning if any harm cause to you

[Mister Micawber]

No, Mouhanaad. In all likelihood, 'cause' in the original sentence means some sort of 'principle, ideal, goal, or movement to which a person or group is dedicated: 'the Socialist cause'; 'the human rights cause'. '
_________________
Native English teacher at Mister Micawber's

[Pooh]

Oh, now I got it.
I thought "the cause" meant "reason" here. That's why
I got confused. This was just one sentence given with no context.
It was easy for me to misundersood.

So, "cause" could be "movement" or "organization" here!
That makes sense.

Thanks!