The book, Aggressors: Patrol Aircraft vs. Submarine (Volume 4) describes in detail the Allied equipment and tactics used against German U-boats and Japanese submarines in the Atlantic and Pacific Ocean combat theaters during World War II.  "Aggressors: Patrol Aircraft vs. Submarine (volume 4)" relates, two new weapons systems that changed the face of maritime warfare in the twentieth century: aircraft and submarines.  While early on in World War II, German U-boats and Japanese submarines ruled the seas, Allied engineers and scientists worked feverishly to develop the capabilities of maritime patrol aircraft.  These counter-weapons possessed a large radius of operation, sophisticated detection and location devices along with advanced weaponry that enabled them to attack enemy submarines both above and below the water.  By late 1943 the hunter had become the hunted and German U-boats and Japanese submarines became the target of roving Allied patrol aircraft, which sank these vessels in ever increasing numbers.  "Aggressors: Patrol Aircraft vs. Submarine (Volume 4)" also recreates a number of decisive battles including the 1944 clash between 49 German U-boats and 23 squadrons of patrol aircraft during the Allied invasion of Normandy, France.  The major sections of "Aggressors: Patrol Aircraft vs. Submarine (Volume 4)" are as follows: 1) Introduction; 2) Forging the Weapon; 3) The Fight Avails; 4) The Battle of the Bay; 5) The Aircraft Triumphant - But Just in Time; 6) The War in the Pacific and 7) Appendix.  In addition to an informative narrative, "Aggressors: Patrol Aircraft vs. Submarine (Volume 4)" includes the following features: 1) Approximately 49 black and white photographs; 2) About 9 color illustrations; 3) 1 four-page color cut-away drawing of a Type VII C U-boat with component descriptions and specifications; 4) 1 three-page color Short Sunderland Mk II profile illustration with specifications; 5) 1 color side-view Type XXI U-boat profile illustrations with specifications; 6) 1 color side-view Grumman TBF-1C Avenger profile illustration with specifications; 7) 1 two-page color cut-away drawing of a Fairey Swordfish Mk II with component descriptions and specifications; 8) 1 color side-view Type VII C/41 U-boat with a schnorkel in 1944 profile illustration with specifications; 9) 4 color side aircraft profiles with specifications (Consolidated PBY-5 A Catalina "Madcat", Vickers Wellington GR Mk VIII, Arado Ar 196 A-3 & Mitsubishi Type O MkII Observation Seaplane -F1M2); 10) 1 giant four-page color illustration depicting a battle between attacking British aircraft and a German U-boat; 11) 1 four-view 1/60 scale color illustration of a Kyushu Land-Based Anti-submarine Patrol Aircraft with specifications and 12) 1 color Consolidated Liberator Mk I profile illustration with specifications.  This book is 64 pages and is in very good condition.  The author is Dr. Alfred Price with Rikyu Watanabe (illustrations).  Edition published in 1990.