Ballantine's Illustrated History of World War II, Weapons Book No 11
Ian V. Hogg
The Guns: 1939-45
This is an excellent overview of artillery and anti-tank guns of the Axis and the Allies during World War II.
The emphasis is on the technology and capabilities of the individual guns, which you'd think would render the prose rather tedious. But author Ian Hogg writes very well and keeps it interesting.
The text is punctuated with numerous photographs and illustrations.