The Naval Battle of Lemnos, fought on 18 January [O.S. 5 January] 1913, was a naval battle during the First Balkan War, in which the Greeks defeated the second and last attempt of the Ottoman Empire to break the Greek naval blockade of the Dardanelles and reclaim supremacy over the Aegean Sea. This, the final naval battle of the First Balkan War, forced the Ottoman Navy to retreat to its base within the Dardanelles, from which it did not venture for the rest of the war, thus ensuring the dominion of the Aegean Sea and the Aegean islands by Greece.

Lemnos or Limnos is a Greek island in the northern Aegean Sea. Administratively the island forms a separate municipality within the Lemnos regional unit, which is part of the North Aegean region. The principal town of the island and seat of the municipality is Myrina. At 477.583 square kilometres (184.396 sq mi), it is the 8th-largest island of Greece.