Guiscard beached his ships at the Glykys river, & would later need engineering work to refloat them

Summary:
[First discussed out of chronological order by Anna Komnene.] With the lower water levels of drought, Guiscard's ships at the mouth of the Glykys were left high and dry, and could not be hauled to the sea. He solved this problem by directing the remaining water into a narrow channel by dykes made of piles and intertwined osiers, reinforced by trees and covered in sand. The water in the channel gradually rose, and allowed the ships to be refloated 
Dates:
1085 Spring-Summer 
Anna Komnene, daughter of Alexios I and historian (Anna 62)
  • Just before the end of the war against Robert 61, she included some details of the commercial privileges extended to Venice; these are better dated to 1082 or (more likely) 1092 (:) Anna Komnene 124.38-126.84
Robert Guiscard (Robert 61)
  • With the summer came drought, and the lower water level in the river Glykys left his ships high and dry; it was impossible to haul them to the sea, causing a serious problem (:) Anna Komnene 125.70-75
  • He used great ingenuity to solve the problem: he directed the remaining water into a narrow channel by dykes made of piles and intertwined osiers, reinforced by trees and covered in sand; the water in the channel slowly rose, allowing the ships to be refloated (:) Anna Komnene 125.75-126.84