Peace on Earth
Thucydides’ statement here implies that war has been a permanent, 365-day-a-year feature of Western society for at least the last 2500 years.
Occasionally we run into small groups of people who are trying to change that, like the organizers of the World Peace Tax Fund (that would allow taxpayers to direct their payments away from the military), and the Year Without War folks, who are working to find a calendar year in which all fighting around the globe would temporarily cease.
Sadly, neither seems to be gaining strength.