Chalcis — the Central Lock in 218 B.C.

Chalcis — the Central Lock — Antigonid Macedon › The Fetters of Greece.

The chief city of Euboea, set astride the Euripus — the narrow strait where the current reverses direction several times a day — and joined to the mainland by a bridge a single fortress could shut. Whoever held Chalcis held the door between the Aegean and the Greek interior, the long island of Euboea, and a dagger pointed across the water at central Greece. From here Macedon overawed Boeotia and, across the strait, even neutral Athens.