In the 1944 book The Big Bosses, by Charles Van Devander, Jaeckle was portrayed as single-handedly controlling the state legislature and helping shape and execute the party's platform.
According to the book, the Albany Legislative Correspondents' Association included in its annual satirical show a song with the refrain: "You've gotta get Jaeckle's O.K.
Dewey won the race and served three terms as governor; Jaeckle is credited with helping lift him onto the national stage.
His law firm, Jaeckle, Fleischmann & Mugel, which was perhaps the most stellar name in the Western New York legal firmament for decades, announced on September 30, 2015, that, as of January 1, 2016, it would cease to exist.
The remnants of the partnership were joined into a Syracuse, N.Y.-based firm and, in a move that stunned observers of the legal profession, the iconic Jaeckle Fleischmann name was not retained.
Among other projects, Jaeckle's father literally built the family church, St. Peter's United Evangelical, completed in 1877.
For years the Jaeckles lived in the house Jacob built at 26 Lemon St. in the "Fruit Belt" of citrus-named streets in the German Near East Side of Buffalo.
After having served in the United States Navy during World War I, Jaeckle returned to New York to build his private law practice.
Jaeckle was elected Erie County (Buffalo) Republican chairman in 1935 and held the position with an iron fist until he resigned it in 1948, ostensibly to devote his full efforts to Dewey's 1948 presidential campaign.
Dewey lost the general election to the Democratic incumbent Governor Herbert Lehman; but the Jaeckle-Dewey partnership was now established and the two men would advance each other's interests off and on over at least the next decade.
As Jaeckle recalled in a 1971 interview with The Buffalo Evening News, "I played the game until after the election, then I quit as state chairman."
The two men later reconciled, and Dewey asked Jaeckle to join his 1948 presidential run against incumbent Democrat Harry S. Truman.
Jaeckle was a liberal Republican who established a tough political machine, ran it with an iron fist, insisted on integrity in party and government affairs, and fostered a progressive agenda.
As Van Devander noted: "Jaeckle spends half of each week at home and during the rest of the time shuttles back and forth to New York City [where his headquarters famously was the Hotel Roosevelt on Madison Avenue at 45th Street], to Albany when the legislature is in session [where his headquarters was the Ten Eyck Hotel], and to other parts of the state.
He is in frequent touch will all of the county chairmen, and succeeds in giving them the double impression that he is devoted to their individual interests, and that he is quite capable of breaking any one of them, politically, who might attempt to put anything over on him.
Jaeckle's papers covering his activities from 1911 to 1992 on the local, state and national levels, as well as recordings and notes of interviews conducted in 1981 by Professor Emeritus William E. Diez of the University of Rochester (NY), are housed at the University of Rochester, Department of Rare Books, Special Collections and Preservation.