You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Seven_Years%27_War

Context:
This problem was compounded when the main Hanoverian army under Cumberland was defeated at the Battle of Hastenbeck and forced to surrender entirely at the Convention of Klosterzeven following a French Invasion of Hanover. The Convention removed Hanover and Brunswick from the war, leaving the Western approach to Prussian territory extremely vulnerable. Frederick sent urgent requests to Britain for more substantial assistance, as he was now without any outside military support for his forces in Germany.

Question:
What Hanoverian leader lost the Battle of Hastenbeck?

Cumberland