I did two things on my seventy-fifth birthday. I visited my wife’s grave. Then I joined the army.Isn’t that a great way to open a book? Intriguing, it draws you in. I guess there’s nothing in it that isn’t implied by the book’s title but still, I like it.Old Man’s War is the story of John Perry who, as we’ve read, enlists on his 75th birthday. The army he enlists with is the Colonial Defence Force and involves him leaving earth, and his former life – he becomes legally dead, behind. The CDF recruits exclusively from 75-year-olds and there are rumours of rejuvenation technology, which is why so many enlist. The truth is slightly more disturbing.The book follows John through the process step by step – leaving earth, initial induction, the treatment, military training, military campaigns. In fact for the first third of the book it’s pretty much one thing after another rather than a plot per se. Then there’s a section when we get to see John and the CDF battling various alien threats. This seemed mostly just to illustrate the variety of aliens and how they need to adapt tactics to fight them. The final section has something more of a plot.I enjoyed this book, particulary parts 1 & 3. A common criticism and one I think I agree with is that you don’t really get a sense of an older person. Once we get to the training and the battles John is just a character we’re following and the fact that he has seven decades of experience doesn’t seem to play into it. I’d've thought at least in terms of the training we’d've see that oldies have less patience for their drill sergeant’s nonsense than your average 19-20-year-old.I was also not a fan of the book’s treatment of the morals of war. The CDF seem to believe in Manifest Destiny and the one character who was given anything to say against this was also a character shown to be stupid by his actions. It’s true I suppose that there’s a constant tongue-in-cheek tone so how much we’re supposed to take any of this seriously is up for question. I’m told that this is dealt with again in the follow-up books. To be honest though I can’t see myself reading them.