This discussion actually reminds me of something I have heard about modern combat ranges - since I don't know where I heard it or when I can't prove it but it is interesting - that these ranges have become shorter in recent years (averagely spoken that is). The reason seems to be more urbanised combat environment combined with a descent size non-target populace (civilians mostly), so the only way to find and defeat the targets is to go from door to door, house to house.
Of course the above is only true when fighting something that is not a 'total war' (a war wherein every resource is made available for the war effort).
In short to have relative close and personal combat with normal high or ultra tech equipment the following seems to be needed:
- Some reason why a place can't be shelled/nuked/shot from orbit reasons can be
- Civilians in the area (when it is illegal or otherwise not a good idea to destroy them)
- Infrastructure you intent to capture and use(like harbours, airfields, spaceports, etc)
- Some defence mechanism that can only be destroyed by a small team of specialists (like the earlier mentioned shields)
- Some or all of the above
- Urbanized environment or any other environment with short lines of sight
- At least somewhat mobile warfare (trenches are not really the thing I am thinking of when I am imaging close and personal combat)