The answer you’re looking for I believe, is Commerce.
The Modern Era spanned at this time. Hope this helps.
It was to pay down their war debts from fighting the French in the Seven Years' War.
power lies with the center government
Most European countries were angered with the Monroe Doctrine the United States implemented especially the countries and empires part of the Holy Alliance after the Napoleonic war. But due to insufficient power and naval forces to implement the doctrine most countries disregard the threat.
