On July 4, 1848, a large contingent of dignitaries gathered in the capital to place the cornerstone of a new monument to honor the memory of George Washington. A major turning point in European history, 1848 also proved significant in US history. Cuba had long been an object of North American imperial desire. The impetus for annexation came from elements in Cuba as well as the United States. Official efforts to acquire Cuba ended with the accession to power of Zachary Taylor and the Whigs in 1849. The impulse toward expansion south into Mexico and the Caribbean gained strength throughout the decade, boosted by private armies that became known as filibusters, from the Dutch word vribuiter, or 'pirate'. The Kansas-Nebraska Act of 1854 shook the edifice of American union down to its foundation. The creation of the Republican party signifies the origins of this phenomenon as it does its institutional expression in the realm of domestic American politics.