The proper method of attack

It would seem that attacking anything in this game should be an easy task that needs little explanation, however there is a complex set of rules that if you follow will maximize your damage, and reduce casualties.
The different troop types
There are four main types of troops (Fighters, Riders, Shooters, and Vehicles) and depending on what you choose when you attack, it can impact the way the game applies damage.
FIGHTERS
Fighters are the first line of defense. They have the highest defense and health of the three major types, but the lowest attack.
Fighters counter Shooters
RIDERS
Riders are considered to the most balanced of the three giving them average attack, defense, and health. They also have the highest marching speed of all troop types.
Riders counter Fighters
SHOOTERS
Shooters have the highest attack of all three major troop types, however they have the lowest defense and health.
Shooters counter Riders
VEHICLES
Vehicles are not considered one of the three major types as their are no vehicle specializations in the game. Vehicles are the weakest of any type in terms of damage, the slowest in terms of march speed, however the highest in terms of defense and troop load.
For this reason vehicles are great for gathering, albeit slower than any of the three major types. They are also great as cannon fodder, just having vehicles in a rally can reduce overall casualties because they absorb a lot of the damage intended for the three major types.
It is important to remember that you are only as fast as your slowest unit. If you attack with only Riders, your march will always attack at its fastest, however if you add even one additional vehicle the entire march will slow to the speed of vehicles, which is not that fast at all. Ostensibly, fighters and shooters will slow down a march as well, however the increase in march time is negligible if compared to vehicles. Thus, any of the troop types combined have a faster march than if you included vehicles.
Understanding Line Formations
Understanding how line formation works will help you to know what troop types to use when rallying. It’s important because the game follows a set of rules on how it assigns offense, defense and damage.
The basic rules are that Fighters line up in the front. They run into battle and absorb the enemy’s front line. They keep your enemy’s fighters busy.
Your Riders then come in behind your Fighters to attack the enemy front line fighters.
Shooters stand in the back and attack the enemy’s Fighters and Riders that are trying to penetrate your front line’s defense.
And any vehicles sit furthest back attacking with projectiles, and absorbing damage intended for your Fighters, Riders and Shooters.
If this sounds familiar it’s because Fighters are infantry, Riders are cavalry, and Shooters are artillery.
These were considered the standard for combat arms since the 14th century when artillery was invented, and are the combat inspiration for the Hasbro© board game RISK™
Rallying attacks
There are two parts to any rally, The Leader, and Followers.
When you rally an attack you are allowing others to join your formation and attack together to maximize your damage on the target, whether this is a Zombie Lair, Building or Sanctuary.
You must think of the Line formation when you create your rally, because as the Leader your choice in troop type impacts damage, health and overall casualties for the group.
Therefore it is important to follow this simple guide in terms of how one should rally.

FIGHTERS ⇒ RIDERS ⇒ SHOOTERS ⇒ VEHICLES
This shows the order in which troops line up in a rally. You can see that if you are the leader and you are using Fighters, then all other types can be added to your rally with varying degrees of impact. Riders, Shooters, and Vehicles will reduce the damage you take, while maximizing the damage your rally will do.
It is however, not recommended that those who join your rally do so with troops of the same type as this can negatively impact the rally. Instead stick to the line formation. If you are the leader whatever of the three troop types you choose, those that join should only join with a troop type that lines up behind or below the leader’s troop type.

The chart above details what troops are safe to join a rally with, based on the Leader of the rally, as well as noting what impact joining with one troop as opposed to a full set of troops, will have on the rally.
Basically if you lead with fighters, join with riders, shooters, and vehicles.
If you lead with riders, join with shooters and vehicles.
And if you lead with shooters, join with vehicles.
When you join a rally with troops of the same type as the leader, the troops are combined, and the damage, attack, and health are averaged among the troops. This can greatly impact the strength of higher tier troops used to lead, when lower tier troops join. This can have an effect on how strong your rally will be against a Zombie Lair.
The impact is similar on Buildings and Sanctuaries, however because Super Rally is an option not available during a rally on Zombie Lairs, you cannot take advantage of it. Super Rallying allows the Leader of the Rally to apply their stats across all rally members, which can be extremely beneficial if you have a strong rally leader, but weaker rally followers.