The most peaceful era? Since WW2 we had, just naming the major ones with US participation, Korea, Vietnam (twice, first the French with US help and the US one), the Second Gulf War, the War on Terror, with highlights in Iraq and Afghanistan (it spanned the globe, earbing the name "global war on terror", and took 20+ years to end with a withdrawal frok Afghanistan). Feel free to count the casualty estimates from wikipedia. Peacefull is sometjing different.