Strategic battlesThe other major change has been to remove the ability for units to stack. More precisely, units are split into Combat and Non-combat, and they do not stack with a similar unit. This means you can still use one unit to protect a worker for example, but you can no longer put some pikemen with you siege equipment to fend off mounted units. “Stack of doom” is no longer possible! It also means you can no longer use a stack of workers to improve a tile in one turn.
A couple more minor changes also add to the way combat is now played out. Firstly, the default move for units is now two tiles; this means terrain can actually slow your units down. Secondly, ranged units can now actually fight at range. Archers and siege weapons can attack two tiles away (later in the game, you get artillery which can fire three) and are also affected by terrain (you cannot fire over hills for example). Transports have also been eliminated with land units able to “embark” and cross the seas on their own. However, a navy is still required to protect them.
All of this combined changes the way combat is now played and allows for some real strategic battles. A small army at a choke point, helped by their terrain can have a real hope of holding out against a larger army. There’s almost a game in itself now with the combat element alone. The “rock, scissors, paper” of the units in Civ V can now be exploited much better. You also get a better overview of an enemy's armies at a glance without having to worry what other units are stacked on a tile.