This first episode focuses on the beginnings of the war, the invasion, the massacres of civilians, the exodus, the first major battles fought in Liège, Namur, Charleroi, Mons, in the province of Luxembourg, but also the fall of Antwerp, the installation of the government at Le Havre, the retreat of the Belgian army to Lyse. Under the command of King Albert I, the troops will defend the last flap of independent Belgium until November 1918.

In order to resist the repressive measures and restrictions of freedoms imposed by the Germans, Belgians take all the risks and organize themselves. On the Yser front, soldiers are trying to survive. In 1915, the Germans attack with asphyxiating gases. The wounded are in the thousands and care services are organized. This is the time when the linguistic divisions of Belgium are exploited by the Germans. They grant the Flemings rights they could not obtain before. 1916 is also the year in which deportations of Belgians are intensifying with a view to compulsory labor in Germany.

Using archival footage, RTBF interviews of veterans in 1964 and historians, look back at the turning point of the First World War. The Battle of Passchendaele, this clash, also called the Third Battle of Ypres, is one of the bloodiest episodes. The English, Canadian and French army reinforcements fought the Germans between July 31 and November 6, 1917. This episode represents a turning point in the war with the Americans who went to war in the spring of 1917. The Russian Revolution October 1917 also changes the alliances. After the loss of ground of the Germans, the Belgians enter the decisive offensives.