Excerpts from Books and Wikipedia
"For an entire century after 1815, by contrast, there was a remarkable absence of lengthy coalition wars. A strategic equilibrium existed, supported by all of the leading Powers in the Concert of Europe, so that no single nation was either able or willing to make a bid for dominance. The prime concerns of government in these post-1815 decades were with domestic instability and (in the case of Russia and the United States) with further expansion across their continental land-masses. This relatively stable international scene allowed the British Empire to rise to its zenith as a global power, in naval and colonial and commercial terms, and also interacted favorably with its virtual monopoly of steam-driven industrial production." [Kennedy: Great Powers, p. xviii] "By 1815 in most parts of Europe the claims of the state to a monopoly of legislation and allegiance within its borders were established in fact if not in law. . . . Part and parcel of this development was secularization, which in Catholic countries involved the exclusion of any form of papal interference and everywhere dictated the subordination of church to state. But the blood that ran through the veins of the state was thin and tepid. To motivate its members, the transfusion of something more inspiring was needed. Increasingly, that was found in nationalism, a secular religion with the ability to unleash devotion and hatred just as fierce as anything experienced during the religious conflicts of an earlier period. . . . Twenty-three years of fighting had probably killed around 5,00,000 Europeans, or proportionally at least as many as the First World War." [Blanning: Pursuit of Glory, p. xxiv, 670]