that in 411 BC the Euboeans closed the strait by mostly rebuilding the dike, with the goal of making themselves part of Boeotia, therefore not an island subject to Athenian hegemony. Diodorus states that gaps had to be left in the dike to allow the Euripus tides to flow through; the narrowness of the remaining passage made the current much more intense. Only a single passage was left navigable, just wide enough for a single ship. There is no mention of the closure of the strait in either Thucydides' History of the Peloponnesian War or Xenophon's Hellenica. Strabo wrote that at an unspecified later date the strait was crossed by a bridge two plethra long (approximately , which is probably an exaggeration). Some vestiges of the artificial dike probably remained, so the gap spanned by the bridge could have been narrower than the channel that existed before 411 BC. Ancient historians do not record the depth of the channel; even the passage under Strabo's bridge may have been scoured by the tides to a depth sufficient for ancient shipping. Procopius reports that during the reign of Emperor Justinian I (527 to 565 AD) there were two channels in the Euripus, the large original channel and a new narrower cleft to the east of it, so narrow that it could be crossed with a single plank of wood. This later stream was later widened to make the present shipping channel. At the time when Procopius wrote, the name of the fortress on the Euripus was probably "Euripus," which had become "Egripos" by 1204, and was adopted and slightly altered to "Nigriponte" by the Latins who occupied the place in 1205. (The name has nothing to do with any sort of "Black Bridge," except as a Veronese or Venetian joke, or folk-etymological corruption or re-interpretation in reference to the old bridge across the channel.) In 1395, Nicola di Martoni came to Negropont during the return from his pilgrimage to Egypt and Palestine. He is clear that the main shipping channel in the Venetian period was on the side of the Boeotian mainland, and mentions the mills on the narrower channel, which he says were sometimes broken in the speed and turbulence of the flow there. We have further information about the shipping channel and its single wooden bridge from various documents in the archives of the Venetian Empire. In 1408, the formation