Question

What is the most expensive war in world history?

Answer 1

That depends on what "expense" you're talking about; more lives were lost in World War II, but more money is being spent fighting The War on Terrorism (ie. Afghanistan & Iraq). We don't have any good way to estimate the costs of other historical wars (like the Trojan War) but up until modern times you did not have as much loss of life or as much money to invest into the process of war.