A large portion of modern wars erupted because aggressive tyrannies believed that their democratic opponents were soft and weak. ~Joshua Muravchik

Except for the Napoleonic Wars, the War of 1812, the Mexican-American War, the Crimean War, the War of Secession, the Franco-Austrian War (1859) and the other Wars of Italian Unification, the War of the Triple Alliance (South America), Franco-Prussian War, the Russo-Turkish Wars, the War of the Pacific (South America), the Boer War, the Spanish-American War, the Russo-Japanese War, the Sino-Japanese Wars, the Balkan Wars of 1912-13, WWI, the Spanish Civil War, Suez, Vietnam, Panama, the Bosnian War, NATO’s bombing of Yugoslavia, the First and Second Congo Wars and the invasion of Iraq, Muravchik’s generalisation holds up pretty well.