The German Democratic Republic (GDR) or East German is a German survivor nation located in eastern Germany.
Great Nuclear War
Because it was split between Allied and Soviet forces, Berlin was not targeted by either side as they both believed they could capture it and didn't want to needlessly sacrifice their forces in the city. Also because so many troops were stationed within Berlin it was irrational to destroy it thus it was not targeted by nukes. The East German military managed to keep it self together with their leadership surviving because the Nuclear Strike against Strausberg sparring the East German military commanders and allowing them to effectively organize a East German and Soviet ground offensive against West Berlin and West Germany while both were still dealing with the Nuclear War. However, some rioting and fighting in the streets between citizens and East German police happened, But thanks to the survival of much of the East German Military/Soviet Forces in Germany and East German/Soviet Leadership many Soviet/East German troops were able to be mobilized from their bases to squash the uprising before it even started. After the capture of West Berlin and the capture of all of Schleswig-Holstein plus all of the city of Hamburg (Not Nuked By Soviets as they thought they could capture it) the NATO/West German forces signed as cease fire with Warsaw Pact/East German forces to end the conflict so both sides could go about piecing their respective nations.
Then the leaders of East and West Germany met to hash out the new border and their relations, after much debate and argumentation they finally agreed that the current border would become the new border and East Germany would get all of Berlin if they returned Hamburg to West Germany so they could use it as their capital. The East and West Germans both agree to the terms of the treaty and sign it. The treaty they signed will officially be known as the Treaty of Hamburg. As time goes on West Germany begins to collapse and becomes North Germany which is effectively a monarchy ruled by the members of House Holler-Hozen. Anyway, East Germany had managed to survive the war mostly intact. Also Colonel Karl Holstein was key in organizing a unified East German Government Post-Great Nuclear War.