When your going onto the battle field it will be harsh just like in the trench. In order to survive you need a gun, gas mask, and a medical kit. Weapons should be provided at the trench. A lot of soldiers made trenches look like their homes so that way they can be comfortable. Poison gas will be used so having a gas mask is important.
A gun will be needed if there is a war. Some guns will fire automatic as long as somebody is holding the trigger. Most guns are simple and aren't automatic which could make it harder to eliminate targets.
A lot of soldiers will be wearing gas masks. This is for when the enemy tries to use poisonous gas on nearby trenches or soldiers. This gas is highly dangerous and kill someone if they inhale it. It is very important that this is kept with somebody if they want to live.
The last thing that is needed is a medical kit. This is probably the most essential thing you'll need in the war. You could heal yourself with it and it could come in handy for other situations.