The history of the First and Second World Wars is difficult to imagine without the submarine warfare waged by their participants. Submarines immediately established themselves as a formidable weapon, posing a noticeable threat to warships, and one of the main types of fleet forces in the fight against enemy communications. It is not surprising that submarine warfare is of such great interest to military history buffs. This is confirmed by the large number of discussions that arise on the Internet, where on historical forums there are heated debates on the topics of whether the German battleship Tirpitz was torpedoed, what were the real successes of our submariners, how legal was the sinking of the British liners Athenia and Lusitania? etc. And, of course, it is worth highlighting the interest in the submarine warfare waged by German submarines during both world wars. This book is a collection compiled from the works of Russian researchers and historians devoted to individual periods and episodes of submarine warfare.