Original: On December 22, 1989, the Brandenburg Gate re-opened when Helmut Kohl, the West German chancellor, walked through to be greeted by Hans Modrow, the East German prime minister.
Simplified: On the 22nd of December 1989, the Brandenburg Gate re-opened when Helmut Kohl, the West German Chancellor, walked through to be greeted by Hans Modrow, the East German Prime Minister.