With the civil war in Syria due to enter its third year and violence breaking out in the Central African Republic and South Sudan, it may be hard to think of the world as a particularly peaceful place at the end of 2013. Yet far fewer people still die of war as did half a century ago. The world has, in fact, become a more peaceful place. So much that in parts of the world, including Europe, war is virtually unimaginable.

The Canadian scientist Steven Pinker showed just how much more peaceful the world has become in his 2011 book The Better Angels Of Our Nature. He found that both the number and intensity of wars has decreased. The worldwide rate of of death from civil and interstate war combined has “juddered downward,” he writes, “from almost 300 per 100,000 world population during World War II, to almost 30 during the Korean War, to the low teens during the era of the Vietnam War, to single digits in the 1970s and 1980s, to less than 1 in the twenty-ﬁrst century.”

There are many reasons for this trend. One is technology. The invention of the atom bomb made was between nuclear states too risky. With the exception of India and Pakistan, no nuclear states have ever waged war on each other directly. The cost in human lives and infrastructure destroyed would be too enormous. The average European country might not even survive a nuclear war altogether.

Another reason is that the global balance of power shifted dramatically after World War II and then again after the collapse of the Soviet Union. During the Cold War, the overbearing might of the two superpowers usually prevented others from pursing policies that could lead to war. The Soviet satellite states in Eastern Europe couldn’t pursue their own foreign policies to begin with. The freedom of Western European countries united in NATO was also somewhat curtailed in that regard. When France and the United Kingdom nevertheless attacked Egypt in 1956, they were quickly forced to give up the endeavor by the United States. Rarely has a European country since initiated military action without the Americans approving it beforehand, if not participating in it.

The humiliation of 1956 made Britain realize its days as the world’s policeman were finally over. The British Empire all but dissolved within the next decade. Unlike France, Britain gave up most of its colonies and overseas territories without much of a fight. The dramatic decrease in war casualties after World War II would probably have been less dramatic had Britain not surrendered its empire so easily.

The postwar spread of democracies, which coincided with decolonization and later the end of communism in Eastern Europe, also had an effect. There were just a handful of democracies in 1945. By the end of the Cold War, some 40 percent of the world’s countries were democratic. Today, about 60 percent is. Democracies don’t usually fight each other so as the number of democracies increases, war becomes rarer.

The greatest democracy of all, America, has also played a unique role in fostering peace. Since the Soviet Union collapsed in 1991, it has deployed its unprecedented military power time and again to end wars, rather than start them — Iraq being an unfortunate exception. The fact that the most powerful nation on Earth seeks neither conquest nor the subjugation of other peoples has contributed enormously to global peace and that is something worth remembering as we enter the new year.