It’s sometimes the case that the most forgettable historical figures furnish the most enduring lessons. Here, Michael J. Gerhardt excavates the remains of some of our least memorable—and least popular—chief executives, along the way adroitly reconstructing the political, legal, and historical legacies that descended, along with these forgottens, to a shallow grave.

The stories of forgotten presidents illustrate how presidential power expands over time because the presidency’s unique capacity for flexibility, determination, efficiency, and energy works to its advantages in protracted contests with other branches and the states.

Take John Tyler, for instance, who “produced one of the richest constitutional legacies of any American president,” despite his wide unpopularity. By raw numbers alone, Tyler’s brief tenure (1841-45) was momentous.  Our 10th president, a Whig, exercised his veto six times, the most of any president up to that point. He was also the first chief executive to have his veto overridden, the first to face an impeachment investigation, and the first to be expelled by his own party. Tyler subverted the Whigs’ majoritarian governing philosophy, which disdained strong executive powers, most prominently by deploying his veto so frequently and skillfully. “Mere regard to the will of the majority,” he declared in an 1841 veto message, “must not in a constitutional republic like ours control this sacred and solemn duty of a sworn officer.”

An unlikely exponent of “energy in the executive,” Tyler nonetheless vigorously defended his appointment and removal powers (“I cannot perceive anywhere in the Constitution .  .  . any duty resting upon the House .  .  . by which it may become responsible for any such appointment”). He also bolstered the president’s prerogative in foreign affairs and deflected congressional investigations through the use of executive privilege.

Stated differently, this is the law of unintended consequences, and it characterized many 19th-century presidents. “All four Whig presidents,” Gerhardt writes, “who had pledged as candidates to weaken the presidency and secure congressional supremacy over domestic policymaking, actually fortified presidential prerogatives and buried their party’s governance principles—and ultimately their party.”

The same was true in a different way of Franklin Pierce (1853-57), an antebellum Democrat and another largely failed president, whose extreme strict constructionism wound up reinforcing the nascent Republican cause. The only popularly elected president not to be renominated by his own party, Pierce ignominiously lost to his own ambassador to Britain, James Buchanan. It was, in Gerhardt’s view, Pierce’s unyielding political philosophy that got him in trouble: In his Inaugural Address, the 14th president declared that the federal government must “confine itself to the exercise of powers clearly granted by the Constitution.” Indeed, by Gerhardt’s count, Pierce vetoed nine bills on constitutional grounds, including, notoriously, legislation promoted by Dorothea Dix that would have allocated millions of acres of federal land to treatment facilities for the mentally ill, because (in Pierce’s words) Washington lacked constitutional authority to act as “the great almoner of public charity.”

Pierce’s extraordinarily tight reading of the Constitution carried over into his cabinet, where he appointed a young Jefferson Davis as secretary of war and Caleb Cushing, an equally strict constructionist, as attorney general. It also permeated his policies, especially on slavery; he pushed vigorously to repeal the Missouri Compromise, which barred slavery in the territories, and to pass the Kansas-Nebraska Act, which empowered states to reach their own conclusions about slavery, independent of federal meddling. Predictably, these policies further polarized the nation, sparked “Bleeding Kansas,” and, ultimately, provoked the War Between the States.