5.1 As is explained in Chapter 28 which considers “proximate cause” in detail, and in common with the ordinary rules of causation, a claim against a war risk underwriter will succeed only if the loss was “proximately caused” by one of the perils for which insurance is given by the policy (a rule with its roots in section 55(1) of the Marine Insurance Act 1906, and which has received very recent attention from the Court of Appeal and Supreme Court in The B Atlantic).1 In other words, the insured must show that the facts surrounding the casualty which the insured object has suffered lead to the conclusion that the loss or damage was caused by one (or more) of the perils against which the policy gives insurance cover. The purpose of this and the following chapters is to consider the decisions which have been made by the courts and, where appropriate, the practices of the London market in relation to each of them.