sentences:  In fact, the entire operation had been rendered moot before it even began, due to events at the wider canal in Zeebrugge.British assessments of that operation had proven optimistic and the channel there had not been properly closed.Small coastal submarines of the UC class had been able to pass through the channel as early as the morning after the Zeebrugge Raid and German naval engineers were able to dredge channels around the blockages at both ports over the coming weeks.