It can be a psychological boost by providing peace of mind and companionship. You can also use fire to produce tools and weapons. Fire can cause problems, as well. The enemy can detect the smoke and light it produces. It can cause forest fires or destroy essential equipment.
Fire can also cause burns carbon monoxide poisoning when used in shelters.
Remember weigh your need for fire against your need to avoid enemy detection. To build a fire, it helps to understand the basic principles of a fire. When you apply heat to a fuel, it produces a gas. This gas, combined with oxygen in the air, burns. Understanding the concept of the fire triangle is very important in correctly constructing and maintaining a fire.