Long before the Cajun Navy hauled last month’s Louisiana flood victims to safety — and even before Hurricane Katrina inspired similar heroism — another volunteer flotilla helped rescue scores of people stranded by rising waters.

That story unfolds in author Glen Jeansonne’s “Herbert Hoover,” a new biography of the much-maligned and perhaps underappreciated president.

Hoover endures in American history as the chief executive on the job when the Great Depression struck, an economic cataclysm that ultimately led to his re-election defeat. But one of Hoover’s biggest contributions to public life happened before he entered the White House, when he was asked to oversee the federal response to the Great Flood of 1927. That flood, which ravaged parts of Louisiana, Arkansas and Mississippi, tested Hoover’s ingenuity and resolve. “The Mississippi not only leaped over its banks; it crashed through or tunneled under containment levees, creating crevasses or breaks in the earthen walls, spreading yellowish muddy water over millions of acres, sweeping away homes and barns, immersing entire towns,” Jeansonne tells readers. “Altogether, more than 25,000 square miles of farmland and small towns were inundated and about 750,000 persons required evacuation or food and medical care.”

Hoover’s first order of business was getting the stranded to safety. “His makeshift rescue fleet consisted of Coast Guard cutters, private yachts and skiffs, motorboats, enormous paddle-wheel steamers loaded with small boats, and a thousand craft built on the spot from crude sawmill lumber, propelled by a thousand purchased motors and manned by volunteers,” Jeansonne writes. “The flood brought out the best in some. Bootleggers lent their swift, maneuverable boats and their navigating skills to the massive rescue efforts. Army and private planes soared overhead, spotting survivors clinging precariously to trees and rooftops, and radioed the locations to the nearest boats, which plucked them from peril. Before Hoover assumed control, between three hundred and four hundred died; afterward, less than a dozen.”

As the flood subsided, Hoover expressed admiration for the volunteer navy that had answered the Great Flood of 1927. “I suppose I could have called in the whole of the Army,” he said. “But what was the use? All I had to do was call in Main Street itself.”

That volunteer spirit is alive and well in America, as the recent efforts of the Cajun Navy made clear. If he were still around, Herbert Hoover would be heartened, but perhaps not surprised.