[citation needed] Historically, and as its name implies, it is modelled after the CSU in Bavaria, the more rightist of the two Union "sister parties".

[4] On 5 February 1990, DSU joined the Alliance for Germany together with the centre-right Christian Democratic Union (CDU) and the now-defunct Democratic Awakening (DA) to form the Alliance for Germany, a centre-right coalition which ran in the first (and only) free East German general election of 18 March 1990.

It achieved its strongest results in the southern districts of Karl-Marx-Stadt, Dresden and Leipzig (that later formed the state of Saxony), where the DSU polled two-digit percentages.

Unlike the other parliamentary parties and a vast majority of the population, numerous DSU members did not accept the Oder–Neisse line as Germany's eastern border (which was finally laid down in the reunification treaty and the Two Plus Four Agreement).

[5] After German reunification was accomplished on 3 October 1990, eight DSU People's Chamber deputies entered into the Bundestag (federal parliament), where they joined the CDU/CSU parliamentary group.

In Chancellor Helmut Kohl's third cabinet, the DSU was represented by Hansjoachim Walther as federal minister without portfolio from October 1990 to January 1991.

Ahead of the first post-reunification German federal election on 2 December 1990, the Bavarian CSU aimed for a deal with the CDU to save its East German offshoot from irrelevance: If the CDU had abstained from competing in a few constituencies in Saxony and Thuringia, thus winning the DSU at least three "direct mandates", the small party could have been spared from the five-percent threshold and might have survived as a regional party.

During the early-1990s, the party received support by the (West German) Neue Rechte ("New Right") movement, in particular by the Criticón magazine of Caspar von Schrenck-Notzing, who also attended DSU meetings.