To lead a civilization from settlers to the stars will require some blood to be shed here and there in the wonderful world of Civilization V. Even though your allies may be content with you on the surface, they're really just using you until they're ready to strike. Be ready for anything with our guide to Civilization V - New Combat Features and Strategy!

No Unit Stacking
Wha? You mean I can’t run around with 40 units in one square, obliterating everything in my path just by hammering in the direction of my opponent’s capital? Such is the case I’m afraid, and it makes having a technologically advanced army that much more valuable than before when only one unit can engage from a given square at a time. It also makes moving your army around en masse more difficult since units cannot end their move in the same square.