WASHINGTON—Robert Mugabe’s defeat in the recent elections in Zimbabwe is the beginning of the end for that country’s octogenarian tyrant. Although the government claims that opposition leader Morgan Tsvangirai fell short of the 50 percent threshold needed to avoid a runoff election, only a massive fraud in the second round followed by a brutal clampdown on demonstrators will keep the man who has governed that country for three decades in power for a little longer.

Joseph Conrad could have been describing Mugabe’s regime when the character Marlow, in “Heart of Darkness,” said about an ivory company: “reckless without hardihood, greedy without audacity, and cruel without courage.” Many lessons can be learned from Mugabe:

The first is that, to a large extent, African anti-colonialism degenerated into a mixture of racism, Marxism and populism to become something akin to the exploitation it had risen against. Of all the colonial-era guerrillas who became masters of their countries after independence, Mugabe was among the worst. His first few years were misleadingly reasonable—he stood for reconciliation, private property and mature relations with the outside world. Only when he was challenged politically did he begin to cloak his tyranny with the ideological “respectability” of socialism and nationalism. Whether it was the massacre of thousands of people from the Ndebele tribe in the 1980s or, in this decade, the violent campaign of land expropriations against whites—most of whom had acquired their land in the open market by then—Mugabe’s denunciation of a neocolonial war of aggression against his country was a perfectly calculated chicanery aimed at justifying his villainy.

The second lesson is that...it is very hard for one country to learn the lessons of another. When, in October 2001, Mugabe took Zimbabwe back to Marxist socialism, countries like Tanzania had already become failures following that same script. Conversely, neighboring Botswana had become a success story by building a democracy under the rule of law based on some aboriginal traditions and by letting free commerce regenerate a country that in 1965 had been the third poorest in the world.

The third lesson is that, pan-African protestations notwithstanding, Africans oppressed by other Africans should expect little solidarity against their dictators from the rest of the region. For years, a group of governments led by South Africa legitimized Mugabe’s atrocities. President Thabo Mbeki and 13 other southern African leaders whitewashed the rigged election of 2002, adding insult to the injury suffered by thousands of opposition supporters who were murdered, beaten or, under an urban planning scheme called Operation Restore Order, expelled from their houses and businesses.

The final lesson is that there is no permanent guarantee that a region will not relapse into despotism or economic misery. In the last decade, it had become customary for world opinion to praise the political and economic progress made by African nations. Some of the praise was justified, but many countries have slipped back into authoritarianism. Nigeria’s government rigged the 2007 elections and earlier this year Kenya’s despot refused to accept his defeat. Both countries had been hailed as models of political transition—Nigeria because of its 1999 constitution that paved the way for civilian rule, and Kenya because opposition leader Mwai Kibaki was able to win the elections and become president after President Daniel arap Moi stepped down in 2002.

It is a testament to the courage of Zimbabwe’s Movement for Democratic Change and of its leader, Tsvangirai, that Mugabe’s ZANU-PF party was defeated in the recent parliamentary elections and that the dictator himself was beaten in the presidential election. Many a challenger would have given up in the face of such overwhelming power. It is by no means certain that Tsvangirai will be tolerant, fair and neutral if he becomes president. But Zimbabwe’s No. 1 priority is to throw the tyrant from power and dismantle the horrific security apparatus whose members are known as “securocrats.” Tsvangirai seems for now the best hope for that to happen.

The great challenge, once Mugabe leaves power, will be to break the cycle of tyranny by placing strong limits on the next president. That will entail an act of extreme sacrifice by the next president—reining in his own powers as the new master of a country that has no institutions worthy of that name. In that sense, the real enemy is not Mugabe but a legacy of political barbarism.