At the same time the Americans raised the guard at Mildenhall and Lakenheath to the level they call Charlie, the second from the top, which is declared when intelligence indicates that terrorist action is likely. What that action might be, no one explains: all the reports agree that the matter is still under discussion among American officials, and that no one has been arrested. The Guardian adds that on the ground there is no specific threat against the base, so that what the Americans saw appears to be more general. Nor do the reports say who holds the guard of the rampart; which is the first thing a commander would ask.

The British Ministry of Defence replied that it does not routinely comment on the activity of other nations, and that aircraft and other assets move regularly according to operational requirements. The American air force declared that its aircraft rotate between installations for many reasons, are hosted under agreements with allies, and that for reasons of operations security it would say no more. Lucy Powell, a minister, stated that she could say nothing of live operations, that the security of the bases is constantly under review, and that firm and quick action is taken where needed. Marco Rubio, the American Secretary of State, said the matter had been addressed by moving people away from the threat. Donald Trump wrote that the Americans were ready and loaded should anything change in the East, but that an escalation was hardly likely.

This is the second withdrawal. In September the B-1 bombers had been taken out of Fairford after men were arrested near the base, five by the count of the Guardian and the Daily Mail, seven by that of GB News; two were later charged under the National Security Act, one of whom is accused of assisting a foreign intelligence service, which the police believe to be Iran's. Andy Burnham, the prime minister, said there were strong indications that Iran had played a part in the affair. Iran's ambassador in Britain denies the charge; but the Revolutionary Guards had declared in July that Fairford and any base used for attacks on Iran were legitimate targets. Earlier reports establish that Fairford had been used by the Americans for attacks on Iran.

Caesar judges the matter thus. Tankers are not the battle line but the supply train; without them neither the bombers nor the air cavalry can go far. Ricketts, formerly national security adviser, said the aircraft were large and inevitably exposed, and guessed that the move was partly an abundance of caution. Rightly. Whoever leaves his baggage where a few men with a single vehicle can set it on fire entrusts the whole campaign to Fortune. Caesar remembers Noviodunum of the Aedui, where he had lodged his hostages, grain, public money and a great part of the baggage: when the Aedui defected and the guards were killed, all was lost at a stroke. From this he learned never to deposit supplies where the guard is at another's discretion.

Others call the withdrawal flight: the British papers write of an exodus, and Greg Bagwell, once in the high command of the British air force, says it is a tactic of temporary survival. Men generally believe what they wish to believe. Sending the baggage to safety is not flight. Yet Caesar does not overlook this: the enemy, whether Iran, as British and American officials suspect, or another, has twice now made the allies move their aircraft with words and a handful of men, without loosing a single weapon. But Fortune, whose power is great in all things and above all in war, works great reversals by small moments; and he who has once learned to give way learns to give way again.

The remedy, therefore, is twofold. First, whoever keeps camps on foreign soil should hold the works and the guard under a single command, and not wait upon his host's constant review; for a rampart is defended not by review but by ditch, sentries and scouts. Second, the British, who do not routinely comment on what is done on their own soil, should decide openly whether they offer a seat of war or not; for he who lends his soil to a war is in the war, whether he admits it or keeps silent. So Caesar holds: to send the baggage to safety is prudence; to leave unfortified the rampart it must return to is cowardice.