In 1922, Louis A. Coolidge and a small group of Massachusetts residents founded the Sentinels of the Republic, a corporation they envisioned as a bulwark against unconstitutional legislation. The Sentinels was especially concerned with the protection of state rights, the limitation of government interference with and regulation of business and other forms of "government bureaucracy", and the threat of international communism.
The Sentinels held annual meetings at which they adopted a "program of policies" which they then published in pamphlet form to arouse public opinion. They sponsored radio addresses, including two series of weekly addresses aired by the National Broadcasting Company, one in 1931 and the other in 1933/4. They also assembled special meetings with "keynote" addresses. A series of eight such speeches occurred in 1927.
In 1924-1925 the Sentinels of the Republic achieved national exposure in their successful attempt to sway Massachusetts opinion against the Child Labor Act. This was Louis A. Coolidge's last and most demanding endeavor as president of the Sentinels; it may well have cost him his life. He persuaded key Massachusetts constituents to oppose the Child Labor Act by "informing" them of its origins, supposedly Bolshevistic, and its foreseeable consequences: denying a teen of the right to help his widowed mother support his brothers and sisters, or even to help in household and farm chores. He also attributed to the proponents of the Child Labor Act a desire to remove children from the influence of their families and the authority of their parents.
After Louis A. Coolidge's death in 1925, Bentley Wirt Warren became the Sentinels' second president and continued his efforts against the Maternity Act and the Federal Education Bill. By 1927 the latter was defeated thanks in part to a flood of speakers, pamphlets, letters and telegrams from members of the Sentinels of the Republic.
In the mid-1930's, under the presidency of Alexander Lincoln, the Sentinels gained in standing and benefited financially, along with other groups of similar inspiration (most notably the American Liberty League), from anti-New-Deal sentiment in the business community. By the 1940's, however, the Sentinels had lost most of their support base, funds and influence, and in 1944 they disbanded.