While the packet boats were thus occupied in foiling the enemy's attempts upon them, the course of events had restored to the post office a footing on land in America. The arrival of assistance from England in May enabled Carleton to attack the American force which had held Quebec in siege since the November previous, and the retreat of the Americans which ensued was not stayed until they had been driven entirely out of Canada. Finlay, who had spent the winter in Quebec, and who has been credited with one of the best anonymous accounts which have come down to us of the conditions of the city during the siege, at once prepared to resume his duties as deputy postmaster general. New York, also, fell again into the hands of the British, owing to the withdrawal of Washington's army in September, before the superior forces of Howe. Here Foxcroft, the deputy postmaster general, and Dashwood, the departmental secretary, were prisoners of war; and Antill, the postmaster of New York, had taken up quarters in one of the war vessels in the harbour. Antill lost no time in returning to the city; and Foxcroft and Dashwood were set free by an exchange for two American officers which took place shortly after.[108] Like Finlay, Foxcroft made preparations for the resumption of business; but for both Finlay and Foxcroft an unexpected thing happened. Vessels with mails began to arrive at Quebec and New York, but the mails were not taken to the post office, although the statute laid it upon shipmasters as their duty to deliver the mails at the post office before they broke bulk.[109] On the arrival of the vessels, the commanders-in-chief directed the masters to send the letters up to their headquarters, where they were gone over by confidential officers, on whom were imposed the duties of handling the incoming mails. The reason of this step will be sufficiently obvious, although the post office professed that they had never seen any good purpose served by it. Even where there was no suggestion of disloyalty among the citizens, there were infinite possibilities of harm in the unguarded utterances, which are constantly occurring in familiar letters. Matters, which it is of the highest importance to keep concealed from the enemy, may be within the knowledge of every citizen, and it becomes necessary either to induce or to compel citizens not to write of such matters. But it was not only against the undesigned harm which loyal people might do, that it was necessary to guard. There was good reason to suspect that in Quebec, as well as in New York, there was a considerable proportion of English speaking people who were by no means well affected towards the government, and who would not hesitate to impart to the enemy any information which they thought might be of assistance.