 Complete the following phrase:  In practice, escort group cohesion was impaired by frequent changes of escort personnel and transferring ships between groups. Personnel shuffling was inevitable as trained crewmen with combat experience were promoted and transferred to the expanding fleet of new ships. Shuffling of ships from one escort group to another was often necessary to maintain escort group strength by replacing ships temporarily disabled by battle damage or the frequent machinery breakdowns of older warships. The following list includes some duplication reflecting reassignments at the time of compilation. The original eight escort groups and the Canadian 14th through 25th escort groups were reorganized into the Mid-Ocean Escort Force MOEF in February and March 1942 with ships of the 9th Escort Group serving as leaders of MOEF groups B1 through B5. The ships of the earlier groups which had only a short-range and were unsuitable for MOEF duty were reassigned to the Western Local Escort Force or duty with coastal convoys or the 