This week is being marked as the 100th anniversary of the killings of more than a million Armenians during the dying days of the Ottoman Empire. Despite considerable opposition from the Turkish government, the anniversary is bringing renewed attention to an often overlooked historical issue, with President Obama in particular facing criticism for not using the word "genocide" to describe the killings.
This didn't happen by accident. The attention placed on the massacre this year is the result of a long and coordinated campaign by Armenia and the Armenian diaspora to ensure that a dark and sometimes disputed part of history wasn't forgotten. It was this campaign that has slowly dragged the Armenian tragedy out of obscure disputes and into mainstream discussion.
It doesn't always work that way, though. In fact, what happens far more often is that the difficult parts of history often are forgotten or ignored. The 20th century was bloody and violent, and while some horrors are at least relatively well-known – the Holocaust or the genocides in Rwanda and Cambodia, for example – others have become mere footnotes in history.
So, in honor of the 100th anniversary of the Armenian killings, here are some of the lesser-known massacres of the 20th century, many of which are considered genocides, too.
Unfortunately, because history is so bloody, this list is far from exhaustive.
The Herero and Namaqua genocide
When Pope Francis referred to the 1915 killings recently and sparked a backlash from Turkey, he not only called the killings a genocide, but also "the first genocide of the 20th century." Even if historians would agree with the former, they might have some disagreements with the latter.
Between 1904 and 1908, tens of thousands of Herero and Namaqua people were killed in what is now Namibia during German colonial rule. These people were indigenous to an area then known a German South West Africa which was the first colony of Germany, a latecomer to the imperial land grab. After uprisings by both the Herero and the Namaqua, a German general in charge of the region ordered that the indigenous people should be "annihilated" or, if this was not possible, expelled from the land.
Unarmed men, women and children were killed by German troops, and huge numbers of Herero and Namaqua people were sent to concentration camps as a form of collective punishment. It's now thought that as many as 70,000 Herero and 7,000 Namaqua died.
In 2004, Germany apologized for the killings, now thought to be the first genocide of the 20th century. Many see the killings as a precursor to the Holocaust.
The Ottoman killings of Assyrians and Greeks
The Armenians weren't the only group targeted during the chaotic collapse of the Ottoman Empire.
It's thought that as many as 250,000 Assyrians, mostly Christians, living in Mesopotamia were killed by Ottoman forces during the period around World War I. Many of those who survived were dispersed throughout the Middle East. A handful of governments, including Armenia, have recognized the killings as a genocide.
At the same time, in Anatolia, the Ottoman Empire killed hundreds of thousands of Greek Christians. While the total number of deaths is unclear, some estimates put it at more than 1 million. Since 1994, Greece has held a remembrance for the killings, which it views as a genocide.
Between 1932 and 1933, estimates say that as many of 10 million Ukrainians – almost a third of the population at the time – were killed by a devastating famine. The mass starvation was of a truly horrific scale: There were reports of cannibalism, and entire villages were wiped out.
It's not just the scale of the famine that merits its inclusion here. Most agree now that the famine was man-made, designed by Soviet leader Joseph Stalin to either eradicate private landowners or perhaps the targeting of Ukrainians as an ethnic group.
In 2006, Ukraine's parliament officially recognized the "Holodomor" – or "Death by Hunger" – as a genocide. But Russia, like the Soviet Union before it, has resisted calls for any compensation for the mass deaths.
The Nanking Massacre
In 1937, during the Sino-Japanese war, the Imperial Japanese Army marched into Nanking, then the Chinese capital. The city, now known as Nanjing, was left virtually undefended, and tens of thousands of civilians were killed, if not more (Chinese historians tend to put the number at 300,000, a higher estimate than their Western peers).
The six-week spree of violence left the city devastated in many ways. The post-World War II International Military Tribunal for the Far East concluded that some 20,000 rapes occurred during the first month of Japanese occupation, lending the tragedy its other grim name: "The Rape of Nanking."
Thanks to some remarkable scholarship over the past few decades, the Nanking Massacre is hardly obscure anymore. But it remains a disputed issue, with Japanese nationalists (and the current Japanese government) accused of downplaying its significance, or even suggesting that it never happened.
The German Expulsions
While the horrors committed by Nazi Germany are well known, what's lesser acknowledged is what happened to the Germans scattered in Eastern Europe after Germany lost the war.
These Germans, who had been left living in places that reverted to Poland, Czechoslovakia and the Soviet Union, had to make their way back to Germany and Austria. Many were forcibly expelled from their homes, some were sent to internment camps.
R.M. Douglas, a historian who studies the expulsions, has described it as "not merely the largest forced migration but probably the largest single movement of population in human history," with more than 12 million civilians forced out. It was effectively what would now be considered "ethnic cleansing," Douglas argued, and, inevitably, masses died – at least 473,000 by one count.