A Roman philosopher coined that war is only beautiful to those who have never experienced it. I've never experienced war and would love to hear an assessment of the abovequote from those who have.

The beautiful stories and reports done by higher ups or officers don't often reflect the hell a soldier would have to go through, many of the legends tell of the glorious battles, making you fantasize about being there beside the hero, when in reality a battle is a bloodbath. Just reading some personal accounts of soldiers of any war, the raw, uncensored truth coming from someone who was there, the grim and dark reality of a battle field, of hunger, often lack of ammunition, the stress, the many cases of ptsd in those who walked the war are enough to assess that the quote is in fact true and hold up quite well.

War is obviously terrible. All I know is my grandfather and his grandfather's stories. One in WWI which left him seriously impaired. The other one was drafted into the Wehrmacht at age 16 in 1945. Wasn't nice for sure, but he spent four years playing football, smoking cigarettes and drinking coke in prisoner of war camp in France and Belgium. He's really liked that time for what's it worth.

Let's see... huge bands of people are roaming the countryside and their main goal is to find and kill the enemy. Depending on the era - with arrows, blades, spears, muskets, pistols, cannons, rifles, grenades, bombs, flamethrowers, toxic gas and so on... During the war soldier will experience moments of intense fear. He'll have to do things he would never do as a civilian (like shooting someone in the face, stabbing and so on). He'll see plenty of dead bodies. He'll see plenty of seriously injured ones. But that's not the worst - if you're a soldier, then war is your "job". You volunteered - so you, at least in theory, should be mentally prepared for the horrors of war. But war also mean the suffering of innocent civilians. You'll see plenty of homeless people. You'll see raped women and killed men. You'll see hungry little kids sitting on the rubble of their homes next to the bodies of their dead parents. 

It's not the cool PC first person shooter you play for fun. It's not a "oh, I'm going on an adventure!" experience. It's not a "you're doing something glorious for your homeland!" thing. It's a bloody horror for thousands or millions of people and nothing will change it. 

I thankfully did never experience war myself. The quotation you mentioned probably aims to hint at the difference between the reality of a war be it for a soldier as already mentioned above or even for a civilian who has to deal with an awful lot of uncertainty and the romantic or heroic wartales often propagated to draw young people to weapons. You even get quite a bit of literature which deals with battles in a very romantic fashion. Though I myself cannot judge how accurate the cruel reality is displayed, I think e.g. Tad Williams describes a rather dark side of war in many of his books.