In September 1991, the president of Afghanistan, Muhammad Najibullah, a former communist secret police chief turned Islamic nationalist, delivered an emotional speech to the Afghan parliament. Najibullah knew the era of foreign intervention in Afghanistan over which he had presided was ending. The Soviet Union had pulled back from direct combat. Radical Islamist rebels covertly backed by Pakistan controlled much of the countryside. Before parliament, Najibullah begged for national unity. His countrymen faced a stark choice, he believed: They could unite to protect Afghanistan’s political, religious, and cultural diversity—including millions of girls in schools and women in jobs—or they could succumb to an obscurantist revolution carried out by religious fanatics aligned with a hostile neighbor.

“No one can carry along all his properties with him to the grave,” Najibullah said, as he pleaded for an end to selfish ambition among the country’s factional leaders. “From king to beggar, all are going to the grave only with two meters of shroud. ... Then what is ambition for?”

If President Hamid Karzai reflected occasionally on his predecessor’s homily, it might brighten the prospects for American policy in Afghanistan. The Afghan president might be advised to reflect as well on Najibullah’s fate, after his exhausted international partners abandoned him: The Taliban beat him to death and displayed his corpse in a Kabul traffic circle.

Najibullah failed, but, toward the end of his presidency, he had many of the big ideas right, as General David Petraeus might say. Under pressure, Najibullah developed a credible political and regional diplomatic strategy to reinforce Afghan national unity in the face of an intensifying Islamist insurgency. At home, he exploited conflicts within the armed opposition and negotiated power-sharing truces with regional, tribal, religious, and militia leaders. Abroad, he appealed to Moscow, Washington, New Delhi, Ankara, European capitals, and the United Nations to support a political process designed to isolate extremists. In speeches, he continually appealed to Afghan nationalism. To foreigners, he pleaded for cooperation on the basis of common interests—mainly, the prevention of a radical revolution that would destabilize South and Central Asia. But for American indifference and the final collapse of the Soviet Union in late 1991, he might have made it through.

Since taking command of the Afghan war effort, Petraeus has stressed the importance of “unity of effort” within the Obama administration. By pointedly repeating that phrase, he has sought to repair the fissures exposed by General Stanley McChrystal and his aides in their undisciplined comments to Rolling Stone. Petraeus is right to demand better of his colleagues, of course, but American unity of effort will be insufficient even if it can be forged; Afghan political cohesion matters much more.