Germany puts its two-front war into action.

Special to The Great War Project

(3 August) On this day precisely a century ago, Germany declares war on France and sends it troops into Belgium.

Now it’s serious. Germany is putting its two-front war plan – against both Russia and France – into motion. German troops also cross into Russian Poland, that part of Poland in the Russian empire.

Then comes an ultimatum from London: Germany must not violate Belgian neutrality But it already has.

Quickly, Berlin realizes Britain will get into the war. Some German leaders react with panic.

Belgium’s King Albert orders his troops to destroy the bridges and tunnels on Germany’s invasion route.

In Luxemburg, German troops spread the false rumor that they are there to stop the French invasion of Luxemburg. But there are no French troops in tiny Luxemburg.

The mood in London quickly shifts. On Saturday it was non-interventionist. By this day, this Monday a century ago, it is now pro-war.

Britain prepares another ultimatum to Berlin. Prepares, yes. Delivers, no, not yet.

The ultimatum is likely to demand Germany’s withdrawal from Belgium. For the moment, though, it remains undelivered in London.

Crowds of people jam central London, eager for any scrap of news.

This afternoon Sir Edward Grey, the foreign secretary, addresses the House of Commons. “It has not been possible to secure the peace of Europe,” he announces sadly.

He speaks for an hour and waits until the end of the speech before he raises the key – the decisive – issue. The violation of Belgium’s neutrality.

Faced with Germany’s ultimatum to Belgium, Grey says, Britain “cannot stand aside.”

Historians report that after Grey’s speech, after he returns to his office, he is heard to remark: “The lamps are going out all over Europe; we shall not see them again in our lifetime.”