It is definitely true that war can be considered as horrifying as hell. There are many reasons that make it so.
First, we have to consider the experiences of the soldiers. The soldiers are forced to commit horrible, cruel acts with no hesitation. They are also required to spend long periods of time with no sleep, little food, extreme fatigue and even sickness without complaint or relief, and in a state of uncertainty regarding their own lives. An example of this were the horrible conditions in the trenches during World War I.
Another point of view we can consider is that of civilians who do not participate in the war, but cannot avoid it. These people often lose their means of livelihood, their home, their possessions and their loved ones to the war. Many have to live in hiding, or in constant fear of death. They also worry for their loved ones who are fighting. An example of this is the destruction that citizens have to face and live with in the city of Aleppo in recent years due to the Syrian civil war.