How many years did the Thirty Years’ War last?

How to get close to this number

Read the question carefully: it asks about a different war from the one the slug suggests. This one really did last the length in its name, which makes it the exception that proves the rule established by its more famous namesake.

The contrast is the point. The Hundred Years' War ran a hundred and sixteen, as this site's companion question explains; this one ran exactly thirty. Named durations are usually rounded approximations, so a name that turns out to be literally accurate is worth noticing as unusual rather than assuming as normal.

The mortality figure is what makes this war historically enormous despite its shorter duration: perhaps a third of the population of the German states, a proportion comparable to the Black Death. Duration is a poor proxy for impact, and a thirty-year war fought across one region killed a larger share of it than a century-long war fought intermittently across two kingdoms.