The detail that is most relevant to the central idea in this excerpt is Washington's realization that the best strategy was to harass the British and avoid risking a general action unless absolutely necessary. This detail highlights Washington's strategic and cautious approach to warfare and demonstrates his willingness to adopt unconventional tactics in order to achieve his goals. It also reflects the central idea of the excerpt, which is Washington's leadership and military tactics during the Revolutionary War. The other details, such as the fact that Washington fell back slowly before striking unexpectedly and the role of French allies in the surrender of Cornwallis at Yorktown, support and provide context for this central idea.