To Properly Defend a city until fellow alliance members can reinforce you, you must keep your cities at a minimum amount of troops AT ALL TIMES.
Your cities should never fall below these troop amounts, this is the BARE MINIMUM:
The Recommended amount of troops you should have in your cities at all times is as follows:
Remember, once you reach these troop amounts in each city you can keep building troops and send them to other cities that are lacking troops. Once ALL of your cities reach the above troop recommendation, you can build any troops you want.
Note: You DO NOT need more than 100k Pikemen or 150k Swordsmen in a city. When you are building extra troops, remember to build useful troops – troops that you attack with. The best, most useful, troops to build are Scouts, Archers, Cavalry, Ballista, and Catapults!!
You can NEVER HAVE ENOUGH BALLISTA or CATAPULTS!
To Properly Defend a city until fellow alliance members can reinforce you, you should have your wall defenses built accordingly.
The Above Wall Defenses are good for defending against Scout Bombs, but even better at defending against Cavalry.
The Above Wall Defenses are the best for defending against Scout Bombs.