The level of detail of battles is meant to be low because it's focused in wars not battles. You are not a war general you are a head of government.
There are still plenty of tactics in Civ 4. Units have different bonuses depending on terrain and other factors. You have to plan where the combat takes place and what types units you want to use.
Some unit types have collateral damage (catapult, trebuchet, cannon, artillery, mobile artillery, etc.), and there are similar mechanics with air units, cavalry, etc.
The game is not short of battle tactics just not the board game inspired mechanic of Civ 5+.
- you can destroy roads (needed for some resources)
- you can also occupy the tile or destroy the improvement (mine/plantation/camp/quarry/etc) needed to harvest a resource
- you can use diplomacy to deny a resource
- you can use a spy to destroy an improvement