A couple of WWII books, reduced on Amazon UK at least:
A Bridge Too Far by Cornelius Ryan. 99p (was £6.99), and if you buy the Kindle book, you can get the audio book for an extra 99p (normally £16.35).
It's probably 20 years since I read this, but as I recall, it's a very readable account of Operation Market Garden.
Crete: The Battle and the Resistance by Antony Beevor. 99p (was £6.99)
I've never read this one, but Antony Beevor is an excellent author, and I'd be interested to learn more about the battle of Crete, so it's going on my to-read list.