Complex sentence: Davin's greatest coup was his jailhouse interview with Riel, which he obtained by masquerading as a francophone priest and interviewing Riel in French under the nose of uncomprehending anglophone watch-house guards.
Split into simpler sentences: Davin's greatest coup was his jailhouse interview with Riel. He obtained this by masquerading as a francophone priest and interviewing Riel in French under the nose of uncomprehending anglophone watch-house guards.