The value of Operation Pluto was controversial. Samuel Eliot Morison, the United States naval historian, noted that the pipelines "proved very useful for supplying the Allied armies as they advanced in Germany."[55] According to the civil official historian, Michael Postan, Operation Pluto was "strategically important, tactically adventurous, and, from the industrial point of view, strenuous".[56] On 24 May 1945, Winston Churchill described Operation Pluto as "a wholly British achievement and a piece of amphibious engineering skill of which we may well be proud."[57]