East Germany decided to upgrade the fortifications in the late 1960s to establish a "modern frontier" that would be far more difficult to cross. Barbed-wire fences were replaced with harder-to-climb expanded metal barriers; directional anti-personnel mines and anti-vehicle ditches blocked the movement of people and vehicles; tripwires and electric signals helped guards to detect escapees; all-weather patrol roads enabled rapid access to any point along the border; and wooden guard towers were replaced with prefabricated concrete towers and observation bunkers. 
Egon Krenz was elected by the politburo to be Honecker's successor. Krenz tried to show that he was looking for change within the GDR but the citizens did not trust him. On November 9, 1989, the SED announced that East Germans would be able to travel to West Berlin the next day. The spokesman who announced the new travel law incorrectly said that it would take effect immediately, implying the Berlin Wall would open that night. People began to gather at border checkpoints at the wall hoping to be let through, but the guards told them that they had no orders to let citizens through. As the number of people grew, the guards became alarmed and tried to contact their superiors but had no responses. Unwilling to use force, the chief guard at the checkpoint relented at 10:54pm and ordered the gate to be opened. Thousands of East-Germans swarmed into West Berlin and the purpose of the wall was deemed now obsolete. The fall of the wall destroyed the SED politically as well as the career of its leader, Egon Krenz. On December 1, 1989, the GDR government revoked the law that guaranteed the SED the right to rule the East German political system, effectively ending communist rule in the GDR.