Part of The Seven Years War, The Battle of Hastenbeck was fought on July 26, 1757. A French Force of 50,000 men engaged an Allied Army of British and Germanic Forces of about 30,000. In June of 1757, France invaded The Electorate of Hanover (the hereditary home of England's King George II). The Hanoverian Army was commanded by The Duke of Cumberland (2nd Son of King George!).
The French had next formed an alliance with Austria (with the goal of breaking the hold of The English alliances with the surrounding Germanic Nations). The French Army marched towards the Village of Hastenbeck (now Northern Germany). The Allied Army formed a defensive perimeter just outside the Village and awaited The French approach. The Allied right flank was positioned near The Harnel River with the main Army and artillery just North of the Town. The Duke of Cumberland had also positioned his Infantry and more artillery on the heights near Obenburg. Cumberland thought that this overlook would provide his defending Armies maximum protection. It didn't.
The French advance arrived on July 26th and began to immediately outflank Cumberland's left line. Reinforcing his center, Cumberland felt that they could withstand the result push of the French. As the French moved for the Allied center, Cumberland's Artillery blasted them – forcing them to move off. Strangely by this time in the battle BOTH opposing Commanders feared that they had lost the battle. Cumberland called in his Reserves to bolster his lines. Seeing this, The French stopped and pressed forward. The Allied Forces (weakened), could not hold and withdrew. As such Hanover would fall to French Occupation (save for the foolish move of allowing The French to see The Allied Reserve advance).