What
. You
never build defenders, I find it alot easier when I attack a city to bring a defender or two. Because the A.I gets protective on their homeland (I would to). And when the A.I attacks your troops your offensive units won't stand a chance unless the A.I's ofenders are really, really obsolete. I'd bring about two caravels of defenders and about five caravels of offenders
.
Better than bringing a defender or two, I'd bring a catapult or a horseman. It's a known fact that you have much higher results when fighting with fast units, Horsemen, Mounted Warriors, Knights, Cavalries. Bringing a defender with those would be totally useless, as it will take at least twice as many turns than the attackers to get to a city. And moving all your Horse army at a rate of 1 tile a turn because you have a spear with you is a very bad idea!
And when the A.I attacks your troops your offensive units won't stand a chance unless the A.I's ofenders are really, really obsolete.
That's the problem:
never ever let the AI attack your offenders. It's a very basic rule and always a good idea. And if you know how to manage troops, you'll be much better defended in a city if you have even something as primitive as a Horseman than if you would have a spear. The spear just sits there and waits to be attacked. With a horseman or you can kill usually 3 enemy attacking units trying to get to your border city, by calculating the moves, retiring from the city when necessary, and always attacking the offenders. if you know how to fight. A spear wouldn't stand 3 attackers, at least unless the RNG gods are really with you!
Let me give you an example. You are in the middle ages. You are at war with a civ, let's say India. They bring 1 Longbowman to one of your border cities. If you have a Pikeman in the city*, the Longbowman, with its 4 offense points will have a high chance of killing the Pikeman, with its 3 defense points. However, if you have in that city a Longbowman, instead of a Pikeman, you can just let the enemy Longbowman advance until it's right next to the city, and attack it. You've got a Longbowman vs. Longbowman battle.... And the Longbowman has 4 attack and 1 defense.
Which odds do you prefer? (bolded parts are your troops)
Longbowman 4:
3 Spearman
Longbowman 4:1 Longbowman
* the city is not over pop 6, and it doesn't have walls. It's anyway very hard to believe you would have walls or aqueducts in a border city, where enemy troops are likely to get.
I often use only offenders to defend my cities. And I can give exact proof that it's, most of the times, better.