The Cleveland Harbor East Breakwater, Cleveland, OH, rehabilitation was completed in 1980. The easternmost 4,440ft (1,341m) was armored with 29,741 two ton (1,814kg) dolosse, slender concrete armor units (CAU) used on coastal structures since 1964. The armor structurally failed within 33 years, a relatively short life for CAU structures. This thesis re-examines the monitoring data from rehabilitation to failure to investigate the deterioration of the armor layer up to the Hurricane Sandy related storm event and includes new information to correlate the remnants of Hurricane Sandy to dolos armor damage that was significant enough to require a new rehabilitation. Probable causes of dolos failures at Cleveland include underdesign, forcing stresses, settlement, ice pressure, continuous surface wave action and extreme storm events. The conditions during the Hurricane Sandy 100-year storm event included a 2 to 3ft (0.6 to 0.9m) storm surge, significant wave heights of 17.4ft (5.3m) and 9.2sec significant wave periods. Post-storm monitoring reinforced the acceptance that most, if not all, new significant dolos damage was the result of the remnants of Hurricane Sandy, resulting in areas of catastrophic armor unit failure along the 1979-1980 dolosse rehabilitation section of the Cleveland Harbor East Breakwater.