Why Historians are sometimes bad at Maths

The Hundred Years' War and the Second Hundred Years' War illustrate how a conflict's name can conceal its duration and the choices about which wars belong together.

A "long century" can span 150 to 190 years. "Age of Imperialism" describes a major feature of the period, though the name can centre imperial powers at the expense of people subjected to imperialism and countries less involved in it.

Historians divide the past into periods to make it easier to write about, study, and teach. Overlapping developments rarely offer a single uncontested starting or ending date.