When protesters started trying in 2011 to overthrow President Bashar al-Assad of Syria, they were part of a cascade of revolutions, known as the Arab Spring, that aimed to oust authoritarian leaders across the Middle East.

While opposition groups elsewhere experienced swift success, the Syrian revolution devolved into a 13-year civil war that has killed hundreds of thousands, displaced millions and carved the country into competing fiefs.

Mr. al-Assad’s stunning fall finally allows Syrians to feel the joy that their counterparts experienced more than a decade ago in Egypt, Libya, Tunisia and Yemen — the four Arab countries where dictators were toppled far more quickly.

Yet while those four states provided a template for revolutionary success, their trajectories since the Arab Spring also constitute a warning.

In Egypt and Tunisia, new strongmen eventually rose to power, crushing efforts to build pluralist democracies. In Libya and Yemen, rival militias jockeyed for control, leading to civil war and the partition of both countries.

“The people who have survived the last 13 years deserve to enjoy the moment before they worry about the future,” said Alistair Burt, a former minister in the British government who helped spearhead its Mideast policy during the Arab Spring.