If he were alive today, William McKinley would understand Barack Obama's 2011 humanitarian intervention in Libya. Like Obama, McKinley confronted geopolitical disorder and economic distress wrought by swashbuckling capitalism. As Commanders-in-Chief and liberal Protestants, the twenty-fifth and forty-fourth presidents both confronted the knotty issue of humanitarian intervention.

Until recently, historians conceived of humanitarian interventionism as a policy with shallow roots in America. Seemingly born from what J. Daryl Charles calls the "defects of the post-Cold War period," American forays into Somalia, Bosnia, and Kosovo have been described as ad hoc and lacking precedent. Such observations reflect a misunderstanding of America's deep history with humanitarian intervention.

At the center of this misunderstanding is religion. The U.S. is the only major industrial democracy where religion still permeates contemporary society as it did three centuries ago. Many analysts have failed to recognize the extent to which religious thinking infuses U.S. foreign policy.

Obama and the Libyan Intervention

Obama's first humanitarian intervention was multilateral and restrained, designed merely to stop an imminent massacre and offer Libyans an opportunity to overthrow dictator Muammar Qaddafi themselves.

Libya's uprising began in February 2011. It was a byproduct of the Arab Spring, prompted by similar issues of government corruption and economic malaise.

Erratic and borderline delusional, Qaddafi was no garden-variety autocrat. Armed with a messianic vision and his revolutionary Green Book, Libya's "Brother Leader" seemed more Mao Zedong than Hosni Mubarak.

But despite his declared benevolence, when provided an opportunity Libyans revolted en masse. Within weeks of the popular uprising's genesis, rebels controlled much of the nation. By early March, they even threatened the capital, Tripoli.

Flush with oil money, Qaddafi employed sophisticated armaments to crush and roll back the lightly armed and untrained opposition. Supplemented by foreign mercenaries, by mid-March government forces slowly pushed toward the rebels' stronghold, Benghazi. Wantonly slaughtering civilians, Qaddafi's forces appeared poised to take the city, destroy the rebellion, and butcher the inhabitants.

As March crept toward April, Qaddafi presented Obama with a stark choice: stage a humanitarian intervention or witness horrendous carnage. Stuck between the realists, who preached against intervention, and the neoconservatives, who urged an immediate NATO air campaign, Obama opted for a multilateral approach. (He was later ridiculed for "leading from behind.")

Transforming a French "no-fly zone" resolution into a UN-sanctioned military intervention, the administration achieved a diplomatic triple play. Endorsed by the Arab League and publicly pushed by the French, the UN approved its first-ever military action to stop an "imminent massacre."

Though messy, NATO airstrikes and military aid did turn the tide and enable the rebels to depose Qaddafi.

The primary influence on Obama's nuanced humanitarian intervention—as with McKinley's intervention in Cuba in the 1898 Spanish-American War—was the long-standing idea of the American sacred-secular world mission, combined in Obama's case with the influence of twentieth-century philosopher Reinhold Niebuhr.