Why is "Age of Metternich" trending?

Wikipedia Overview

The Concert of Europe was a general agreement between the great powers of 19th-century Europe to maintain the European balance of power, political boundaries, and spheres of influence. Never a perfect unity and subject to disputes and jockeying for position and influence, the Concert was an extended period of relative peace and stability in Europe following the Wars of the French Revolution and the Napoleonic Wars which had consumed the continent since the 1790s. There is considerable scholarly dispute over the exact nature and duration of the Concert. Some scholars argue that it fell apart nearly as soon as it began in the 1820s when the great powers disagreed over the handling of liberal revolts in Italy, while others argue that it lasted until the outbreak of World War I and others for points in between. For those arguing for a longer duration, there is generally agreement that the period after the Revolutions of 1848 and the Crimean War (1853–1856) represented a different phase with different dynamics than the earlier period.