American electoral politics have been dominated by two major political parties since shortly after the founding of the republic. Since the 1850s, they have been the Democratic Party and the Republican Party.
Some historians have suggested that two-party systems promote centrism and encourage political parties to find common positions which appeal to wide swaths of the electorate. It can lead to political stability which leads, in turn, to economic growth.
During the First Crusade, Christian knights from Europe capture Jerusalem after seven weeks of siege and begin massacring the city’s Muslim and Jewish population.