The unresolved Glorious decision matters more than its rumored mission

Which past event would you observe to settle an important historical uncertainty?

Establish what Glorious was actually doing, though every leading explanation still leaves her two-destroyer escort contrary to doctrine.

A direct observation of Glorious's last voyage could establish why she sailed with so little protection. The competing explanations do not solve the central operational problem: both an urgent return and a secret mission required a stronger escort than two destroyers. Contemporary practice around Courageous shows that the Royal Navy understood carriers needed a larger protective screen even during anti-submarine operations.