copied from other sources....
This is a guide i wrote near a year ago..Besides basic stuff, one thing worth notice is defense mechanism.
By Inquisition from s2
i will discuss the core of travian, combat outcome. Understanding how combat is calculated is vital to using your army effectively.
Disclaimer: this is purely my speculation. I have done a lot of experiments with combat sim as well as real attacks so I think this is generally accurate.
- Combat outcome is decided by 3 factors:
+ Combined attack power (cavalry + infantry, including weapons upgrades).
+ ram and wall level
+ pop difference
+ A big army is always better than a small army: you lose a lot less troops when attacking the same defense. A good mix of cavalry and infantry attackers is also important. However, infantry is usually the most effective (based on attack power and crop consumption), so focus on them first. The exception is teuton, TK is such a great unit and the best horse among 3 races, i would recommend at least 3 axes:1TK.
Here's the chart to compare units:
+ Never split your offense, never split your defense. Overwhelming defense and offense is the key of victory in combat.
+ Rams are very important vs walls. Suggestion: 300-500 rams upon reaching a considerable army.
+ Pop difference is not small. The bigger the more loss. Always be wary of reinforcement trap before (much) smaller targets.
Now i will go step by step, explaining each factor and how it affects the battle:
+ The mechanism of attacking and defense power.
I will post some examples using combat sim with the assumption of there is no wall and pop is equal between attacker and defender to demonstrate this factor accurately.
1st rule: in combat, despite there are infantry and calvary, everything is calculated and combined to an ONE exact attacking power number. The attacking value is static (which means it doesn't change)
That means if i have 100 imps and 50 ECs, my attacking value would be: 100*70 + 50*180 = 16000 atk power.
The defensive value is tougher to calculate as there are 2 defensive values, infantry and calvary. Where would an unit use more of its infantry defense than calvary defense ? That depends on the attacking power composition.
Let's take a look at the above: the attacker is using 100 imps and 50 ECs. So the whole attacking power = 7000 infantry atk + 9000 calvary atk.
-> the ratio between infantry and calvary atk power is 7 infantry:9 calvary
A= 7000 Ai + 9000 Ac = 16000
Now's the defensive attacking power is determined by this formula. We name total defensive infantry value = dI and total defensive calvary value = dC.
D= di * (7/16) + dC * (9/16)
Calvary and infantry defensive power is proportionated with the attacker's infantry and calvary power.
That means, if the defense consists of 330 praets
Total infantry defense di = 330*65= 21450
total calvary defense dC= 330*35=11550
D value would be: 21450 * (7/16) + 11550 * (9/16)= 9384 + 6496 = 15880
So we have A = 16000 and D = 15880
Now go ahead and confirm the formula for defensive power, put 100 imps and 50 ECs vs 330 praets to see the outcome.
You can simply remember this: the defensive value is determined by the ratio of infantry:calvary of the attacker. It's automatically proportionated to the ratio of the attacker.
Remember this is very important when you go up against an one sided defense, that means too much infantry defense or too much calvary defense.
Many times, it's favorable not to use your full army, instead using only either infantry or calvary to kill the enemy.
The famous case on travian forum is this:
20 TTs attack 200 clubs = 8 TTs dead
20 TTs + 20 swords attack 200 clubs = 13 TTs and 13 swords dead
Many people don't understand why with more troops, there are more troops dead. As you can see the answer is simple. it's because clubs infantry defense is 20 while calvary is only 5. In the 1st case, those clubs only use their calvary defense value, but in 2nd case, they use part of infantry value as there are swordmen in the mix.
This is just an extreme example, but it matters for other units as well, so you should always pay attention to what you are attacking.
- The 2nd rule of this section is: casualities are decided by A versus D, between these 2 values. The formula of casualties is unknown, I'm not sure the exact formula but i can describe it relatively accurately.
Basically the rule is: the bigger the better. The bigger A or D is, the less loss A or D take. Examples:
1000 imps vs 1076 praets (A= D) -> 1000 imps dead
2000 imps vs 1076 praets (A= 2D) -> 727 imps dead
3000 imps vs 1076 praets( A= 3D) -> 606 imps dead
4000 imps vs 1076 praets (A=4D) -> 540 imps
5000 imps vs ... -> 494
6000 imps vs ....-> 460
20000 imps vs 1076 praets(A=20D) -> 306 imps
40000 imps vs 1076 praets(A=40D) -> 253 imps
80000 imps vs 1076 praets (A=80D) -> 217 imps
Do you see the pattern ?The rate of decline in losses slows as the ratio of attackers to defenders gets very large. What does this mean ? This means it's not that really important whether you have 40 or 80k imps in this particular battle, you only lose 40 imps less with 80k imps. However, from 1k to 2k you lose 270 imps less. This means, bigger army than defense is very important, especially the first few examples (A=2D to A=5D) you lose A LOT less, it's vital in minimize your loss by having sufficient attack power against a defense. Before attacking, THINK about whether your army is big enough to destroy the defense without too many losses. If it's possible to wait to build more troops, WAIT. It's much better to lose part of your army then all of your army. I'm killing people's troops daily and i still have a big army is because those loss are so small it's irrelevant. But can a people with 3k army keep up with my offensive rate? The answer is NO because then he would take considerable loss to his army daily.
Defense value also works the same way, just switch D for A in those examples and we have a good illustration why more defense is better. In short, the more the better. And passing the hurdles (the first few examples where A=2D to A=5D) is very important.
This is also the reason why split armies should be avoided by all cost (except when one main army is building at maximum speed, but that's less likely possible due to the strain of crop). Having ONE MAIN ARMY is the best, then you can decide whether you want to build a sub army if crop allows.. You can choose to build it in a cropper capital or a normal village. A cropper capital will relieve you from the hassle to transfer crop or have to reinforce your troops to garages, however a normal village gives you the advantage of gb,gs.
Personally i don't like GB but that's open to different playing style.
Same respect for defense, DO NOT split your defense in every village, pick most important villges and defend them. Try to guess where the main attack is among the fakes.
+ Ram and Wall:
Wall adds a modifier on top of D value. That means at level 20 city all, total defensive value is multiplied by 1.8. 81% more defense, that's A LOT.
City wall is the most effective wall, next to palisade then earth wall. However city wall is also most prone to rams, then palisade and last earth wall as almost indestructible (you need roughly 300 rams to take down 20 earth wall wall)
Question: How does ram work during combat with defense ?
Answer: First off ram has attacking value of its own (with the same as catapults) so they add on attacking value overall.
Second, rams destroy wall DURING combat. That means, the more rams, the better to take down a wall.
We will use big number of troops here to nullify the small attacking power of rams.
City wall level 20
1. 50k imps + 100 rams vs 40k praets => all impms were killed, city wall is brought down to level 11.
2. 50k imps + 200 rams vs 40k praets => 2.3k imps left + 9 rams left city wall destroyed
At this point, most players think "ah so i have enough rams, because city wall is destroyed"
The answer is WRONG, yes you have enough rams to "barely" destroy a wall, not comfortably destroy a wall. The wall is being brought down slowly and during that process, it still helps the defense a lot.
3. 50k imps + 400 rams vs 40k praets=> 11k imps left
So 200 rams make the whole difference between 2.3k imps left to 11k imps left.
Never underestimate wall and having a good number of rams when you're sweeping is important
The more rams the better, i would personally suggest the minimum number of ram = 1% of your army crop. Mean if you have 5k army, you should have at least 50 rams to go with that. Upon reaching 10-15k army, i suggest 300-500 rams (earthwall takes a lot more to take down than city wall).
+ Pop difference:
The last and most annoying modifier, pop ratio. Travian admins decide it's pretty cool to punish big pop player (the ones who put the most work into account) so we have this stupid mechanism where. the more pop you are, the more loss you take during combat
It's really something that we have no control over, we can't really catapult ourselves to make us smaller can we ? we can't really tell our targets "hey guy, build up a little bit so i won't loss that much".
It's still good to notice this difference though because it's HUGE when your target is much more smaller than you.
5k imps vs 1k praets (pop equal, no wall) -> 433 imp lost
5k imps vs 1k praets (attacker is 10 times bigger in pop) -> 794 imps lost
Bullshit, isn't it ? However this can work to our advantage, it's much better to kill big armies at a smaller pop player. Also be aware before you attack a much smaller player, it might be a trap!
Note: if you attack a bigger pop player, you don't get any bonus, the mechanism will treat as you two as equal pop. This is why big simcity is so tasty, you lose a lot less and the bounty is much bigger