The Bourbon monarchy was restored once more, and the victors began the Congress of Vienna, to restore peace to the continent. As a direct result of the war, the Kingdom of Prussia rose to become a great power on the continent, while Great Britain, with its unequalled Royal Navy and growing Empire became the world's dominant superpower, beginning the "Pax Britannica". The Holy Roman Empire was dissolved, and the philosophy of nationalism, that emerged early in the war, greatly contributed to the later unification of the German states, and those of the Italian peninsula. The war in Iberia greatly weakened Spanish power, and the Spanish Empire began to unravel; Spain would lose nearly all of its American possessions by 1833. The Portuguese Empire shrank, with Brazil declaring independence in 1822.