1945 is an alternate history written by Newt Gingrich and William R. Forstchen in 1995, describing the period immediately after World War II wherein the United States had fought only against Japan, allowing Nazi Germany to force a truce with the Soviet Union, after which the two victors confront each other in a cold war which swiftly turns hot.
In reality, "Fortress Europe" was the Nazi concept of making German-occupied Europe impregnable to the invasion, which was clearly coming since the Allies started massing their forces in Britain in 1943. In D-Day this "fortress" was decisively breached.
At the start of the novel, the United States, having defeated the Empire of Japan, is in no mood to enter a new war, and Americans accept the fait accompli German domination over most of Europe. An alternate Cold War seems in the offing; even the United Kingdom, with a German-dominated Europe at their doorstep, squander much of their resources on a colonial war in the former French Indochina.
U.S. President Andrew Harrison (a fictional character) has a summit with Adolf Hitler at Reykjavík, Iceland. The meeting goes badly, the two leaders sharply confront each other, and Hitler secretly decides to accelerate preparations for a surprise attack on both the United States and the United Kingdom. As part of these preparations, a beautiful German spy seduces and suborns the White House Chief of Staff and makes him a key German spy.
The book's protagonist, Lieutenant Commander James Martel, at the incipient Head of Naval Intelligence at the American Embassy in Berlin, is one of the few who suspects the gathering storm, watching the new weapons displayed at the parade commemorating Germany's victory over the Soviet Union and encountering the well-known commando Otto Skorzeny who is his main opponent throughout the book.
Skorzeny makes meticulous secret preparations for raids to destroy the American atomic bomb programs in Oak Ridge National Laboratory and Los Alamos National Laboratory. (During the war with Japan, the Manhattan Project was put on the backburner. So, in 1945 the United States is far from already possessing a nuclear bomb.) The bulk of the book is devoted to Martel, back in the United States, getting a glimmering of the threatened attack and unsuccessfully trying to sound a warning.
The German raid takes place, and though the Germans are eventually beaten back, the raid causes great damage, killing key scientists and setting the American nuclear program behind Germany's; moreover, the Germans seize the uranium mines in the Congo region, while launching all-out war against the United Kingdom.
The book ends with a cliffhanger: Erwin Rommel invades Scotland, the British facing a desperate fight, and Prime Minister Winston Churchill imploring the Americans "come quickly, this is much worse than 1940".
The promised sequel, provisionally called Fortress Europa, has yet to be written, though many years have passed and the writers had meanwhile completed a different alternate history trilogy (beginning with Gettysburg: A Novel of the Civil War).