In a statement which would come back to haunt him, First Secretary of the Socialist Unity Party and East Germany's State Council chairman Walter Ulbricht stated in an international press conference that "no one has the intention of erecting a wall" to separate the western and eastern parts of Germany.

Two months later, on Saturday, August 12, 1961, the leaders of the GDR attended a garden party at a government guesthouse in Doellnsee, in a wooded area to the north of East Berlin, where Ulbricht signed the order to close the border and erect a wall.

At midnight, the police and units of the East German army began to close the border and by Sunday morning, August 13, 1961, the border with West Berlin was closed.

Residents of the area awoke to find East German troops and workers tearing up the streets running alongside the border to make them impassable, and installing barbed wire entanglements and fences along the 156 km (97 miles) around the three western sectors and the 43 km (27 miles) which actually divided West and East Berlin.

The initial barrier, built slightly inside East Berlin or East German territory to ensure that it did not encroach on West Berlin at any point, became the Berlin Wall proper on August 15 when the first concrete elements and large blocks were put in place. The true nature of the Wall also began to manifest itself with soldiers manning the fledgling Wall with orders to shoot anyone who attempted to defect.

Elsewhere, chain fences, walls, minefields, and other obstacles were installed along the length of the inner-German border between East and West Germany.

The effect was devastating. Travel between the two Germanys was severely restricted and in many cases impossible. East Germans lost any opportunity to move to the West. Many families were split. East Berliners employed in the West were cut off from their jobs. West Berlin became an isolated enclave in a hostile land.

More than just a barrier, the Berlin Wall, which the East German government claimed was an "anti-Fascist protective rampart," soon became a symbol of the divisions in the Cold War world which would last for a further 28 years.