Germany to join the Federal Republic (under the constitution of the Federal Republic of Germany). Article 146 provided the possibility for unification of all parts of Germany under a new constitution. After the peaceful revolution of 1989 in East Germany, the Volkskammer of the GDR on 23 August 1990 declared the accession of East Germany to the Federal Republic under Article 23 of the Basic Law; and so initiated the process of reunification, to come into effect on 3 October 1990. Nevertheless, the act of reunification itself (with its many specific terms and conditions; including fundamental amendments to the West German Basic Law) was achieved constitutionally by the subsequent Unification Treaty of 31 August 1990; that is through a binding agreement between the former GDR and the Federal Republic now recognising each another as separate sovereign states in international law. This treaty was then voted into effect on 20 September 1990 by both the Volkskammer and the Bundestag by the constitutionally required two-thirds majorities; effecting on the one hand, the extinction of the GDR and the re-establishment of on the territory of East Germany; and on the other, the agreed amendments to the Basic Law of the Federal Republic. Amongst these amendments was the repeal of the very Article 23 in respect of which the GDR had nominally declared its postdated accession to the Federal Republic. The two German states entered into a currency and customs union in July 1990, and on 3 October 1990, the German Democratic Republic dissolved and the re-established five East German (as well as a unified Berlin) joined the Federal Republic of Germany, bringing an end to the East–West divide. Politics Political life in West Germany was remarkably stable and orderly. The Adenauer era (1949–63) was followed by a brief period under Ludwig Erhard (1963–66) who, in turn, was replaced by Kurt Georg Kiesinger (1966–69). All governments between 1949 and 1966 were formed by the united caucus of the Christian-Democratic Union (CDU) and Christian Social Union (CSU), either alone or in coalition with the smaller Free Democratic Party (FDP) or other right-wing parties. Kiesinger's 1966–69 "Grand Coalition" was between West Germany's two largest parties, the CDU/CSU and the Social Democratic Party (SPD). This was important for the introduction of new emergency acts—the Grand Coalition gave the ruling parties the two-thirds majority of votes required to see them in. These controversial acts allowed basic constitutional rights