Final answer:
Frederick Bligh Bond's success at Glastonbury Abbey was due to his diplomatic skills and the peaceful Treaty of Jaffa, which he negotiated with Sultan al-Kamil during the Fifth Crusade.
Step-by-step explanation:
Frederick Bligh Bond's success in his investigation of Glastonbury Abbey can best be explained by his effective use of diplomatic skills and strategic agreements, most notably the Treaty of Jaffa, which he concluded with Sultan al-Kamil in 1219. This treaty allowed for a peaceful resolution of the conflict between Christians and the Ayyubids during the Fifth Crusade. Rather than using force, Frederick utilized negotiation and compromise to achieve the crusade's objectives and thereby demonstrated an outstanding ability to navigate complex political and religious landscapes.