Battle of Spicheren - Wikipedia

On August 6, 1870 the Battle of Spicheren took place in which the Prussian army defeated France. From the article:

The Battle of Spicheren, also known as the Battle of Forbach, was a battle during the Franco-Prussian War. The German victory compelled the French to withdraw to the defenses of Metz. The Battle of Spicheren, on 5 August, was the second of three critical French defeats. Moltke had originally planned to keep Bazaine's army on the Saar river until he could attack it with the 2nd Army in front and the 1st Army on its left flank, while the 3rd Army closed towards the rear. The aging General von Steinmetz made an overzealous, unplanned move, leading the 1st Army south from his position on the Moselle. He moved straight toward the town of Spicheren, cutting off Prince Frederick Charles from his forward cavalry units in the process...

The battle was not intended by Moltke, who wished to keep Bazaine's army on the Saar river until he could attack it with the II army in front and the I army on its left flank, while the third army was closing towards its rear. The aging General Karl von Steinmetz made an overzealous, unplanned move, and proved that he did not have the slightest notion regarding Moltke's plans. Leading the I army south from his position on the Moselle, he moved straight toward the town of Spicheren, cutting off Prince Frederick Charles from his forward cavalry units in the process. The First Army advance guard (14th Division, VII Corps) under General Georg von Kameke, advancing on west from Saarbrücken on the morning of 6 August, found the bridges still intact, and seeing the opportunity that this offered, pushed on to occupy the high ground just beyond the town. The French 2nd Corps under Frossard, who had withdrawn his 2nd Corps back about one mile to the Spicheren plateau, had abandoned these heights in order to take up what he considered to be a position magnifique, fortified between Spicheren and Forbach. Frossard distributed his corps as follows: holding the right and centre was the division of General Laveaucoupet, deployed along the heights, with two companies entrenched on the Rotherberg. On the left General Charles Nicolas Vergé’s division occupied Stiring and the Forbach valley. General Bataille’s division was held back in reserve around Spicheren; in all, counting the corps cavalry and artillery, some 27,000 men with 90 guns."