The Lusitania sailed into a zone Britain knew was dangerous

Larson establishes that British naval intelligence, through the code-breaking unit known as Room 40, had access to intercepted German communications revealing submarine activity near the Irish coast where the Lusitania would pass. Despite this, the ship received only a general warning notice rather than a naval escort or a specific rerouting order, even though smaller, less valuable ships were sometimes given protection in the same waters.

Larson doesn't claim outright conspiracy, but he lays out the pattern of decisions — withheld intelligence, unused escort ships, a captain given vague rather than precise instructions — that made the ship far more vulnerable than it needed to be. The admiralty's caution about revealing that codes had been broken may have cost lives by keeping specific threat information away from the people best positioned to act on it.

Takeaway: institutional secrecy, even for legitimate reasons, can quietly transfer risk onto people who never get to make an informed choice.