WHEN RUSSIA invaded Ukraine last year, the Black Sea seemed unlikely to become much of a battleground. The Ukrainian navy, after all, had only one warship, which it was forced to scuttle as Russian troops advanced on the shipyard where it was being repaired, in the city of Mykolaiv. Snake Island, a maritime outpost guarding the western approaches of Odessa, Ukraine’s biggest port, fell to Russian attackers on the first day of the war. Odessa itself braced for an amphibious assault that would have cut Ukraine off from the sea altogether.
