As seen above, deaths from warfare in the UK have come down significantly from historical times. The chart below illustrates the reduction in European homicides since the year 1200. The bottom graph demonstrates the large peak in genocides in the middle of the 20th century, with subsequent decline. More from Pinker:
Believe it or not—and I know most people do not—violence has been in decline over long stretches of time, and we may be living in the most peaceful time in our species' existence. The decline of violence, to be sure, has not been steady; it has not brought violence down to zero (to put it mildly); and it is not guaranteed to continue. But I hope to convince you that it's a persistent historical development, visible on scales from millennia to years, from the waging of wars and perpetration of genocides to the spanking of children and the treatment of animals.
...The extraordinary 65-year stretch since the end of the Second World War has been called the "Long Peace", and has perhaps the most striking statistics of all, zero. There were zero wars between the United States and the Soviet Union (the two superpowers of the era), contrary to every expert prediction. No nuclear weapon has been used in war since Nagasaki, again, confounding everyone's expectations. There have been no wars between any subset of the great powers since the end of the Korean War in 1953. There have been zero wars between Western European countries. The extraordinary thing about this fact is how un-extraordinary it sounds. If I say I'm going to predict that in my lifetime France and Germany will not go to war, everyone will say, "Yeah, yeah; of course they won't go to war." But that is an extraordinary statement when you consider that before 1945, Western European countries initiated two new wars per year for more than 600 years. That number has now stood at zero for 65 years.
And there have been zero wars between developed countries at all. We take it for granted nowadays that war is something that happens only in poor, primitive countries. That, too, is an extraordinary development; war used to be something that rich countries did, too. Europe, which traditionally has been the part of the world with the biggest military might, is no longer picking on countries in other parts of the world, or hurling artillery shells at one other with the rest of the world suffering collateral damage. This change has been extraordinary. _Edge.org
But can we expect this drop in violence to continue? To answer that question, one must look at demographic trends. The populations which are growing are those that exhibit higher rates of violence, and those that are shrinking are the ones which exhibit lower rates of violence -- as a rule. For example, populations within Africa, Asia, and South America which exhibit the world's highest rates of violence are also generally showing the highest birthrates. Even within advanced nations, the subpopulations which show the highest rates of violence also exhibit the highest birthrates.
If these demographic trends continue, the shrinking, less violent populations, are apt to either die off, or be killed off. The violent and prolific populations may just inherit the world.
In modern politically correct cultures, violence is often condemned outright, without qualification. But violence in defence of one's life, family, and property is the hallmark of civilisations which survive. Without the threat of defensive violence, the weak and passive become prey to any violent person who comes upon them.
Law enforcement cannot be everywhere, protecting everyone. Any society which forbids individuals from using violence to protect themselves or their property is a society in decay. The law is meant to be taken into the hands of citizens. Otherwise the law will serve only a corrupt oligarchy.
Humans have the choice whether they will transition back to another violent phase of history. If that is the choice, they are going in the direction which will accomodate that decision.