After our look on the possibilities of attacking we will now examine defending a little bit. We have stated in the previous article that Civ IV is a game that favours the defender. Let`s see what you can do to save your empire from the raging hordes...

A. Defense basics

One of the major factors for any defensive effort is terrain. Just to recapitulate: "Flat" terrain gives no defense bonuses, hills give +25% bonus (with an additional +25% for archer units), forests and djungle give +50% and hills with forest or djungle on it +75% bonus. This bonus gets subtracted from the attacking unit's strength. Also rivers have to be taken into account: Attacking across a river gives a -25% penalty to the attacking unit (with the exception of units with the amphibious promotion), and it also prevents the effect of roads before Construction. Ideally you want to use the tiles with those bonuses for defensive purposes, and you want to deny those tiles to the enemy. If you have any of those tiles with defense values close to your city - those are the key strategic tiles you have to especially focus on.



Here the enemy has moved in and wants to attack your city. In front of your city is a forested hill tile, which gives +75% defense bonus (the key strategic tile here, much like the forests around the city). If the enemy can move his stack onto that tile you will have a hard time killing his units. It would be much better if you could attack his units on the flat tile next to it. So you should take the tile yourself, and position a unit or two on it.



Here the defending player has put 2 Archers on the tile to deny it to the enemy. As you can see the odds of attacking are not that great, and if he wants to take that hill, he has to sacrifice some of his units (with Archers on a forested hill the attacker will lose at least 3, most probably 4 and maybe even 5 Axes – depending on his RNG luck) – which lessens the amount of units potentially threatening your city. The attacker will - instead of potentially losing much of his offensive power - rather move on the flat tile in front of the city, where your chances of killing the stack are much better.

Remember: Always deny key strategic defensive tiles to the enemy, and keep the defense value of a tile in mind when moving units! Chop your forests close to your city to make it easier for you to defend!

B. Planting cities

Defending begins even before you plant your first city. The choice of a city location is one of high impact on your chances to defend yourself later. Ideally your cities are on hills, because all units get the +25% terrain defense bonus and Archers get a free additional +25%. The choice of a city location is determined by 4 main factors:

• food resources
• strategic resources
• terrain defense bonus/ability to defend
• rivers

The only exception to this is playing Modern or Future Era games – there food resources are not that important, what counts is the availability of strategic resources (mostly oil/aluminium) and the ability to defend the city.

For your first city moving to a hill is not always the best move though – do not move to the hill if it is a grassland hill (it only will give 1 hammer on the city tile itself, not 2 hammers like a plains hill) or if you lose out on food or strategic resources by doing so. By moving you lose 1 turn of production and tech while the +25% defense bonus is not enough to justify that sacrifice in most cases.

Now you have planted your first city, and you look for potential other spots as you produce your settlers. In general you just have to remember the above mentioned criteria to identify good city spots. But now you have to take an additional strategic point into account – the interaction of your cities as front line. Sometimes you cannot plant an otherwise great city spot just because it’s a huge strategic risk. To clarify this we will look at an extreme situation: The double front.



The player here has planted two cities, both in very viable spots. The first city has a 2 hammer marble plant, gets grassland sheep as food and iron as strategic resource. The second city has a grassland pig and an irrigated corn for a quite decent city spot. And still planting those cities is horrible from a strategic point of view. Not only those cities are planted on flat terrain, but worse: They offer a prime target because of their positioning. Take a look at that situation:



The opponent has moved in a stack of Swords. It’s easy to see that he threatens both cities potentially, and he has one advantage over the defender: He knows where he will move and attack, the defender has to react. Now he will move his units at the latest possible time – 00:00, the turn shift. The defender then has practically no chance to react and shift his units to the threatened city in time, even if he has enough units to repel the attack if he can concentrate them in one city. A planting like that is even worse with two movers – this situation is ideal for attack patterns like the fork. What would a better plant look like?



Here the player has avoided a situation like the one above – he has a clear front (a fork with two movers is still possible though once the forests are chopped, but it's less devastating - the tiles he can land on are right next to the stacking point for the defensive troops!), and he can now organize his defense from the middle tile:



When under attack the player can reach every city from the middle point where he stacks his units. This is a basic pattern of planting cities in the best way for defense – as a rule triangular or rectangular shapes which allow defense to be organized from a central point in your land are best.

The sentry net

One of the main reasons for successful attacking is the use of the surprise element. Defending in a short timeframe of only 8 seconds (the normal delay after moving your units) is a much more demanding task than when you know several turns ahead that, who and what is coming towards you.

The consequence for the defender is building up a good sentry net. As sentries fast moving units are best, such as Scouts, Chariots or Horse Archers. If the points you have to cover are near to your land you can also use Warriors, Archers or Spears. Replacing especially Scouts and Chariots over the course of the game with units that get terrain defense boni and are thus harder to kill is a good idea.

Especially in the beginning of a game - when production is short and needed for building up your civ - the installation of a good sentry net is no easy task. The benefit is huge though, as you can devote more resources to development then - you can get the units only when they are needed, as you have some turns of warning.

When planning your sentry net you should consider the following:

1. First take a look at your land. Where are spots where the opponent could easily move in? Where would you move in if you were in his place? Take especial care of the nooks in your cultural borders!

2. Position your sentries on hills, preferably forested hill tiles or ones with djungle on it. Your sentries gain +1 visibility range this way and can defend better.

3. If your sentries get killed, replace them as soon as possible. Especially in the middle of a game the killing of sentries can signal a coming attack - so some extra vigilance doesn't hurt!

4. In a teamer game proper scouting and getting sentries in place is a team effort - so communicate with your teammates who is responsible for checking which area.

The example below shows a good use of the sentry net:



B. Advanced defending

B.1. Roading

In the article about attacking we have already seen the benefit of intelligent roading. The use of roads is even more vital for organizing a successful defense. Remember that the big advantage of the defender is mobility (HE can use the roads in his lands) and the shorter lines of supply. To use this advantage fully roads are essential. Therefore you should connect your cities as soon as you can spare workers for the task, and make sure you road the shortest possible supply line.

Roading also can play a role in directly attacking the offending enemy stack. Hitting a stack before it reaches defensive terrain is most times only possible with the use of roads. In teamer games it's also very important to road your teammates on your borders early - this way you can support each other in case of an attack.

Connecting each other via roads also enables resource trading, which can be a life saver in a tight situation. Being able to get metal gifted by your teammate can be the difference between living and dying. Another way of connecting to your teammates is researching the Sailing tech, because rivers then work like road connections between the teammates.

In later eras (Renaissance upwards, and especially Future and Modern) you should be aware that roading can be a risk if done excessively though. The reason for this is the easier availability of the Commando promotion (for an example for the use of the Commando read the article about attacking). In those eras more than one road leading to and away of a city can be an additional risk one has to take into account.

B.2. Collateral damage

Collateral damage is one of the basic concepts of the Civ IV battle engine. The following units are capable of inflicting collateral damage to enemy units: Catapults/Hwacha, Trebuchets, Cannons, Artillery, Mobile Artillery, the Cho-ko-Nu (Chinese UU replacing the Crossbowman) and all Air units. The amount of collateral damage as well as the amount of affected units differs from Catapults to the Stealth Bomber and generally increases as the units become more advanced.

The importance of collateral damage results from the fact that only one unit can damage several units while attacking. Compare this to simply attacking with a normal unit: The normal unit scratches the defender as well, but damages only the defender. While collateral damage is very important for attacking (where it is sometimes the only chance of killing a city, especially in the early eras) it is also a key element of defending. If you have enough units that can inflict collateral damage even big stacks can be handled. The unit most commonly used for that purpose is the Catapult. It plays a major role even up to the Industrial Era. Just a short demonstration:



The opponent has moved in 36 Rifles. The player has a defensive force of 11 Cavalry and 24 Catapults ready. Now the defender hits the stack of Rifles with all his Catapults. Of course all Catapults die, but the result is impressive:



The Rifles are scratched to an extent where the Cavalries have good odds at mopping them up. As a result the defending player in the example kills 11 Rifles and loses no Cavalry. This means the attacker now has only 25 scratched Rifles left for the attack, while the defender still has 11 Cavalry able to promote next turn. Instead of the 25 Catapults the defender could have had 11 Rifles (close to same amount of invested hammers), but with those 11 Rifles he would have had only 50% odds at every attack. In the best case he kills 11 Rifles with a fully intact 25 Rifles in the rest of the enemy stack, in the worst case he loses 11 Rifles and kills nothing while 25 Rifles remain totally undamaged. The advantage of collateral damage is pretty obvious here.



Or in hammers:

24 Catapults lost x 33 = 792 invested / 11 Rifles lost x 73 = 803 invested

With using the Catapults the defender has not only changed the dynamic of the situation to his favour, but also gained a slight advantage in production over his opponent.

B.3. Flanking

Flanking can be very effective if you have to defend against an opponent who brings a lot of siege weapons with him. All mounted units except Chariots are capable of flanking. Flanking also works with totally unpromoted units, so the Flanking I + II promotions only have an indirect effect on it. If the flanking unit attacks a stack flanking damage is applied on the siege units if the flanking unit survives the attack (either wins the battle and kills the attacked unit or withdraws from battle before it is killed itself). As the Flanking promotion increases the chance of withdrawal significantly it indirectly also increases the chance of flanking the siege units in the stack. The amount of damage is calculated by the relative strength of the defending unit to the attacker. The stronger your defending unit is in relation to the attacker the less flanking damage is done. Artillery and Mobile Artillery are immune to Flanking though.

Flanking has immediate uses when your opponent otherwise cannot kill you or even capture a city without siege units. Often it's your only chance to flank and kill the siege units - even if it means sacrifcing your mounted stack. Flanking is incredibly powerful from Medieval upwards - the reason why it is disabled in CCC games. But enough theory, here is an example how this works:



The enemy has moved in with a stack of Swords and Catapults. But the defender has a stack of Horse Archers, with which he flanks the stack. The result:

3 of the 4 Catapults die, the defender is safe. If he had kept his units in his city and waited for the stack to hit it he would have faced severe problems.



B.4. Satyagraha

Satyagraha is no fancy meal from your Indian restaurant next door - it is the philosophy of non-violent resistance by Mahatma Gandhi (http://en.wikipedia.org/wiki/Satyagraha). What has this to do with Civ4 MP and defending? Well, some years ago I came across a very interesting variant report from Kylearan of Realms Beyond. He played a game where he was building no military units at all, and he was using the term Satyagraha for his last resort defense in case he would be attacked - he wanted to defend with workers (read the very well written report on Kylearan's website). Something similar is possible in Civ MP. But of course we are not trying to confuse the path-finding of our opponent (we're playing vs. humans after all ), but we will use a feature of the Civ4 battle engine to our advantage.

In Civ4 attacking is limited by two factors: 1) movement points, 2) specific ability of the unit to attack. 1) is obvious - if the unit has no movement points left, it cannot move and therefore not attack (but it can defend). If the unit has movement points, 2) kicks in - every unit is limited to 1 attack per turn. If 1 attack per turn has been used the unit cannot attack any more this turn regardless how many movement points are left. The only exception to this are units with the Blitz promotion, for those the only limit are actual available movement points then. The trick now is to make the enemy use up that one attack per turn before he can kill your city so that you can get a defender in time. I will explain how this works with a basic example (and add the real nifty one later). Look at this situation:



It's early in the game, and the opponent has moved in two warriors on you. You are working a 2 hammer tile for 3 hammers total so you can slave your Archer next turn. Of course you could slave a Warrior now so he is ready to defend next turn when the enemy's Warriors can attack. But slaving a Warrior is something you don't want to do because it's ineffective. If you leave your city empty though it is likely to get killed next turn - the first Warrior scratches the defending Warrior, and the 2nd one has good odds then. But you still have a Scout you can move - and you move him into the city. Now if the 1st Warrior attacks and scratches the unit the Scout is still in the city, and when the 2nd Warrior attacks and kills the defending Warrior he cannot capture the city - the Scout is still in it. This gives you the time to complete your Archer and get rid of the other Warrior later. Another example of this:



Your opponent has saved money and upgraded a Warrior into a Dog Soldier (which gets +100% vs. Melee Units). Now slaving a warrior is totally useless as the Dog has >99% odds on both consecutive fights. Still you can slave your Archer next turn, so all you need is to survive one additional turn - and your Scout can give you that turn. You move him into the city, the Dog kills the Warrior of course, but can't capture the city and has used up his attacks for this turn. You slave your Archer, and you have survived!

And now for the real Satyagraha! Look at this:



You have planted a city, but the enemy has sneaked a Chariot in. You Archer will be ready to defend next turn, but - the Chariot is able to hit this turn. All you got is the Scout and the two Workers behind the city. Now moving the Workers into the city won't help because unlike Scouts Workers can't defend, the enemy would just kill the Scout, take the city and the workers (so you basically gift him two workers and a city kill). Still there is a way to save the city, and now the things we said at the beginning come into play. If we force the enemy to use up his attack ability before he can attack the city this will give us the 1 turn needed for the completion of the Archer. And so our two brave Workers readily sacrifice themselves for the common good of the empire:



The path to the city is blocked now, if the opponent wants to gain a position where he can hit the city he has either to a) use up all movement points for this turn by moving into the forest or b) kill a Worker and use up the ability to attack. This buys the time to complete the Archer and be relatively safe next turn (and yes, as experienced players will see at once, the player should work the forested hill instead of the plains forest if the 2 hammers matter - the enemy could move on it at 00:00, thus automatically changing the tile allocation and forcing the Archer to not complete in time). The enemy has killed the Worker, but the city is safe despite >99.9% odds:



Please note this doesn't work if the city is completely empty. The reason for this is attacking units don't need any attacking abilities to capture empty cities. So, next time you have to desperetaly save a city and no units at hand - maybe your Workers can help you out! It happens more often then you think