The Second Battle of Dernancourt, known to the Germans as Unternehmen Sonnenschein, was fought on 5 April 1918 near Dernancourt in northern France during World War I. It involved a German Army force attacking an Australian defending force, and resulted in the German capture of much of the forward sector of the Australian front line which ran along a railway line between Albert and Dernancourt. The Australian 4th Division had been sent south to help stem the tide of the German spring offensive towards Amiens, and held a line west and north of the Ancre river. The main German assault force was the XXIII Reserve Corps, which concentrated its assault on the line between Albert and Dernancourt. Their attack at the boundary between the Australian 12th and 13th Brigades overwhelmed the Australian front line troops near Dernancourt and captured some support trenches. An Australian counter-attack in the afternoon wrested the initiative from the Germans and their attack petered out, leaving the Australians still in possession of most of the high ground northwest of Dernancourt, barring the way to Amiens.