Germanos II (1223-40) was the Orthodox patriarch of Constantinople at a critical period after its fall in 1204 to the fourth crusade, when Byzantium looked doomed to irrelevance, as its emperor and patriarch eked out a shadowy existence in exile at Nicaea. Germanos II's major achievement was to give his office renewed substance by obtaining recognition of his ecumenical authority not only from the community of Orthodox churches, but tacitly from...