March 18, 1990 elections confirmed the policies of the East German centrist parties, the 'Alliance for Germany' (including the CDU, Christian Democratic Union and the SCU, the Christian Social Union), and their path towards unification (Paterson & Smith, in Smith 1992, p25). This trend was emphasised in the slogans of street marchers, which changed from 'we are the people' to 'we are one people' (Paterson & Smith, in Smith 1992, p14). Here Kohl's personal canvassing of support in the East German elections was essential (Hancock 1993, p226). It was decided that general elections on both sides would only occur after unification.
International acceptance was also required for this transition. Although alliance arrangements made with the US, France and Germany in 1954/1955 had provisions for moves towards a peaceful reunification of Germany, Britain, under Thatcher's leadership, was in early 1990 opposed to the idea of a rapid reunification. As soon as early 1990 top German officials were visiting France and Britain to allay suspicions, while in February an Ottawa (Canada) meeting between the 4 main World War II allies and German representative attempted to iron out various concerns, especially those concerning borders (Rothwell 1990a, p11). These negotiations resulted in the Two Plus Four Talks, in which the USSR, the US, France and Britain (the four powers of WWII) and the two Germanies ironed out many aspects of the path to unification.
On 3 October, 1990 the parts of Germany torn apart at the end of World War II were united. This was done not through negotiating a new constitution, but by an adoption of existing constitutional arrangements implicit in the Federal nature of West Germany. Under Article 23 of the Basic Law of the West German state, 5 new Lander or regional states were incorporated into the Federal Republic (Paterson & Smith, in Smith 1992, p9). This was a faster path than the use of Article 146, which states that 'Basic Law shall cease to be in force on the day when a constitution adopted by a free decision of the German people comes into force', i.e. the creation of a brand new constitution (Paterson & Smith, in Smith 1992, p25), perhaps through the use of referendums. West Germany simply expanded its federal structure to include what had once been East Germany.