For an successful attack, you need allways 4 units of light artillery (or more)
If supply is plentiful, 2- 4 units of heavy artillery are added.

Place your artillery so, that at least 2 enemy victory points can be bombarded.
Fortify your artillery post and your victory points with cheap trenches. 4 units infantry per victory point are sufficient as a defense against counterattacks.

Enough supply for an basic attack is provided by 6 divisions of infantry and a level 2 supply depot. For an offensive, the best possible infantry divisions should always be used.

Focus your attack on one enemy victory point.
The perfect target for the breakthrough is on the sides of the map and is near a forested area. Forests provide cover for your infantry.
After the successful breakthrough, the remaining victory points are captured with a flanking attack.

Use the first 3 - 5 minutes of gameplay to prepare the attack on the chosen victory point with an artillery bombardment. A balloon is very useful to spot your targets. Otherwise, a wave of cheap infantry scouts has to be sacrificed.

With light artillery, you destroy enemy balloons, machine gun nests, mortar emplacements and barbed wire. Only 4 cheap salvos are needed for this explosive work.

With heavy artillery, you bombard the enemy infantry stationed inside their trenches. Forward positions and/or doubly occupied trenches have priority. One salvo does usually enough damage to make the coming melee easier for your men.

It's best to form a thin but deep column with your attackers, like on the picture below.
Then, your men have to face fewer enemies and you can penetrate deeper into the enemy lines.

Aim for weakly fortified sections of the enemy trench system. It's best to move your attack column between two trenches, so your men will get less often stuck. If available, use the cover of forests!

10 units of infantry are just right for a successful attack. Cheap, basic infantry leads the charge and "tanks" enemy fire. Expensive special infantry follows behind.

Enemy artillery is pretty weak in the open field. Only particularly dense barrages should be dogged by your men. But keep moving, standing troops are easy prey.

If available, the smoke from smoke shells lasts approximately 45 seconds. This allows you to lay a covering field in front of your attacking men.

The most important thing for a successful attack is the widespread suppression of the enemy with your light artillery.

Just before your army comes within firing range of the enemy, begin with the suppression bombardment. Try to cover as many enemy trenches as possible with the cannon's suppressive bombardment. With luck, up to 4 trenches per cannon are possible. Without this suppression, no attack is possible.

When your attacking men reach the first trenches, move the suppression to the rear enemy positions.

Meanwhile, your heavy artillery will bombard unforeseen surprises like hidden MG-nests or mortars.

Your infantry tries to get into the suppressed enemy trenches as quickly as possible.
Timing is crucial. Through practice you will learn how to use light artillery bombardment for the best support of your attacking troops. Without suppression, your men will be immediately shredded in the open field.

The creeping barrage is a slightly more expensive method of suppression. But with it, more area is suppressed and covering smoke is produced. Start the creeping barrage just before your attacking men come under enemy rifle fire. For maximum effect, place the barrage so, that the 3rd line of fire is directly on the frontmost enemy trench (like on the picture above in step 2).

Quickly move your infantry into the enemy trenches. Elite troops have the best melee stats and are therefore to be preferred. Ideally, you have already weakened the opposing enemy lines with artillery fire (step 1)

Morale is important in close combat. Troops with low morale flee more quickly. Reduce enemy morale with gas, tanks, siege bombardment or create war fatigue with previous attacks.
Improve your troops' morale with canteenas or aid packages.

Grenadiers and Flamethrowers are can openers and can attack the enemy from above inside their trench. This saves your men from costly hand-to-hand combat. Use them together with normal infantry when charging or to mop up enemy strong points in the second wave of attacks. Be careful, they only have a short range and will quickly come under your own suppressive fire.

Move forward step by step while keeping your troops inside the trenches as much as possible. The trenches protect your troops. Advance along the trenches until the enemy is driven out of the position. Meanwhile, keep enemy rear trenches suppressed and bombard enemy strong points with heavy artillery.

Quickly call in fresh reserves and man the conquered trenches. Replace decimated troops with fresh ones.
To "counter" enemy counterattacks it's often best to place some troops outside the captured trenches and let them shoot at the enemy from the open field.
But keep the enemy attackers constantly suppressed with your own light artillery. Otherwise your men will be easy prey on the open field...

Try to get to the northern edge of the map quickly and gather your infantry for the next attack.
There you are out of range of enemy artillery.

Take the next closest enemy victory point with an flanking attack. Enemies in trenches cannot target flanking attackers and are therefore vulnerable!

Occupy the enemy trenches on a front as wide as possible (like in the picture below).
Flamethrowers and Grenadiers are particularly deadly in flanking attacks.
But don't forget suppressing the enemy with your light artillery.

Repeat steps 1) - 4) for the successful attack

Aircraft are an useful support. To be tactically successful on the battlefield, you must always outnumber your enemy. This refers to the battle map, globally you can field fewer aircraft than the enemy. However, the existing squadrons must then be deployed concentrated on the battlefield and local air superiority has to be achieved.

• Use balloons and a reconnaissance mission. They provide map information and lure the enemy fighters out of their base.

• Make sure, that you always have more fighters in the air than your enemy has. A ratio of two to one is safe. Ideally, you will lure all enemy fighters out of their base and destroy them with your numerical superiority and technology.
  

• Send up your bombers against the enemy artillery, tanks and weapon emplacements. If the airspace is still contested, 1 - 2 fighters must accompany your bombers as an escort

• The distraction mission is very effective against enemy infantry. Use them simultaneously with your infantry attack or to intercept enemy reinforcements on the open field.

• Flak will be suppressed and destroyed with your artillery if necessary.

Tanks are the easiest way to achieve a breakthrough. They cause great damage, demoralize the enemy, crush barbed wire, "tank" enemy fire and give a morale bonus

Always use tanks as a battering ram in your attack together with other weapon systems. Infantry follows right behind, artillery suppresses threats.

Light tanks are mobile and, after breaking through, can intercept enemy reinforcements in the open field and destroy artillery in the hinterland.

Tanks are not indestructible. Avoid enemy grenadiers, mortars, bombers and artillery strikes.

Why go through the hassle of conquering enemy trenches when you can simply blow them up?

- 4 siege cannons destroy 40% of enemy trenches and reduce enemy morale. A useful support for all kinds of attacks.

- With 15 cannons you destroy 80% of enemy defenses. However, you need a lot of supplies for this. With research, the cannons can be improved significantly.

- With the precision strike or undermine you can precisely eliminate dense pockets of resistance.
In addition, you can use the precision strike to take out densely manned enemy trench clusters.

The gas attack drives unprepared soldiers out of the trenches and causes heavy casualties. It also destroys morale and reduces enemy attack power.
Of course, this is especially useful, if you already have a few units inside the forward enemy trenches.
Then you can shoot at the enemies jumping out of the trenches.

It is best to start the gas attack shortly before your attacking men come under enemy rifle fire.
Aim the gas at densely occupied trench clusters in the rear and try to gas as many enemies as possible.
Protect your men with gas masks or stay in trenches out of the gas clouds

The enemy can protect against it with gas masks. Upgrade your gas to bypass these countermeasures.

• Strategy (the bigger picture)
  To win the war you have to make your enemy commit his resources as poorly as possible. This allows you to use your own resources (manpower and supplies) even better.
  The best way to achieve this goal is to create as many Saillants as possible.
  Saillants (like Verdun or Ypre) are bulges in the front and extend deep into enemy territory. Saillants, with their large surface area, tie down a huge number of enemy divisions.
  See Verdun in the picture as an example. It borders 4 enemy regions and binds a large number of enemy troops.
  Ideally, you create such a large area with your own sailllants that enemy troops are thinned out and effective defense against your attacks becomes impossible.

• Operation (the right target):
  
  In order to achieve your goal of creating Saillants, you have to attack the right regions.
  Regions with few stars and many opportunities to attack from many sides are the ideal targets to create a new Saillant.
  See the example below, Vouziers has 2 stars and can be attacked from 2 sides. This means you can conquer Vouziers in a single turn. Your enemy doesn't have time to reinforce Vouziers.

• Tactics (the method of breakthrough):
  
  Always use the element of surprise when attacking your target. To get the element of surprise, your arms should be as small and inconspicuous as possible.
  Supply and technology (like tanks or gas) act as leverage and compensate for your numerical inferiority.
  Back to the Vouziers example. It is defended by 6 divisions, we have only 5 divisions for the attack. The enemy would never expect an attack from a smaller army, so we have the element of surprise!
  Our numerical inferiority is compensated and levered out with the technology of poisonous gas.

• Tips to get the element of surprise:
  
  Avoid attacks with large Doom stacks. Doom stacks are powerful, but also very predictable and rob you of the element of surprise.
  It is better to divide your troops over the frontline and attack at the same time on a surface as large as possible.
  However, Doom stacks can be useful defensively. They distract the enemy and tie up his troops on the choosen site. You can then attack the thinned enemy elsewhere!
  
  Espionage and counter-espionage are important and an often neglected factor in the game...