On 2 August, Napoleon and the Prince Imperial accompanied the army as it made a tentative crossing of the German border toward the city of Saarbrücken. The French won a minor skirmish and advanced no further. Napoleon III, very ill, was unable to ride his horse and had to support himself by leaning against a tree. In the meantime, the Germans had assembled a much larger army opposite Alsace and Lorraine than the French had expected or were aware of. On 4 August 1870, the Germans attacked with overwhelming force against a French division in Alsace at the Battle of Wissembourg (German: Weissenburg), forcing it to retreat. On 5 August, the Germans defeated another French Army at the Battle of Spicheren in Lorraine.