Attackers going for Full conquest but...

I have been looking for wars where the aggressor went for full conquest but failed to do so, and then settled for something smaller. There must be tons of example, such as the winter war.

Im interested in the subject because i want to see how the aggresor's final objective affects his tactical/strategical way of doing war.

example: First punic war, where it was all about who owns Sicily. The objectives for both side was not a full conquest/annexation. This made the war different then the Second punic war(of course theres other factors which i will not get in).

Anyway, im looking for:

- wars were the aggresor started for full conquest but settled back for less
- If you can, explain how going for full conquest affected the way they fought.

 

Well at least once it was the plague that saved Persians from Roman conquest because on the battlefield they were already broken.

 

But I think that there are also opposite examples, the agressor attacks without any plan and is not not trying to conquer all the country that he invaded but his luck and circumstances allowe him to do so. I think that Caesar makes good example, he didnt plan to conquer Gaul but achieved it. On the other hand he did plan to conquer Britain but failed and didnt achieve anything.

 

One that i thought of is teutoburg forest - they focused too much on getting one big battle where the romans had an edge, and that led to blindly going into a disadvantageous ground(and ignoring some safety issues), which then led to their slaughter...