The first one that I finished was Osprey Campaign #237: The Fourth Crusade 1202 – 04: The Betrayal of Byzantium. Now, I've listened to several podcasts about this subject over the last year or so, so it was nice to be able to look at maps and plates showing much of the action that I'd heard, so this one was particularly good to read. I still can't believe that machinations that led to the "Christian" crusaders to waste most of their military might on Christian targets.
Next was Osprey Men-At-Arms #500: Armies of Castile and Aragon 1370 – 1516, essentially another crusade, the armed forces that kicked the Moors out of the Iberian Peninsula. I found this one fairly interesting.
Then, Osprey Men-At-Arms #494: Forces of the Hanseatic League: 13th - 15th Centuries deals with a subject that I knew barely anything. Various cities in the north of Germany essentially mercantile in nature band together to join forces to get what they want.
Next was Osprey New Vanguard #225: Republican Roman Warships 509 – 27 BC which deals with ancient naval vessels, clearly. Rome's not known as a maritime power. The data here shows a bit more clarity than that.
I'm reading another, but that's for another time.