I want to start off this post with a quote from John Wilsons' web site:
"So, what makes a good book for boys? At the simplest level, a whole bunch of dead guys."
This is what John Wilson writes about best. Well, not just about dead guys, but they are a big part of what he does write about. He takes an episode from history that deals with war or disaster and writes about it in a way that appeals to boys.
Here's another quote:
"If a book relates to a boy’s attraction to war, it must also portray the other side—the rats, the rotting corpses, the terror of life in the trenches—in at least an equally convincing way. It must be graphic and many people are not comfortable with that."
No he doesn't glamorize war, disaster or exploration, he makes it real by writing about the horror and darkness, but he does so in ways that appeal to young male readers. Lots of descriptions about things that girls tend to dislike intensely (but not always) -
"What doesn’t get in the way of a boys’ story is a detailed description of a neat weapon. Boys like to know how things work. They will happily read a description of a World War Two Tiger tank that comes directly from Herr Krupp’s owner’s manual. How thick was its armour plating? What size of shell could it stop? How fast could it go? Where did the crew sit? What calibre was the machine gun in the turret? What happened to the crew if a shell got through the armour plating?"
His stories are fascinating, fun, gruesome, bloody and just plain exciting. If you haven't already tried one, I strongly urge you to do do so. My favourite was 'Where Soldiers Lie' which is an amazing and captivating account of one of the events during the Indian rebellion in 1857.
If you are at all interested in reading the full article that I got the quotes from you can find it here. It's a fascinating essay on writing for boys, that is well worth reading.