While Louis was in Hampshire, the barons whom he had left in London, with some of his French troops, overran the eastern counties; they sacked some of the towns, ravaged the country, exacted “tenseries” everywhere, and returned “laden with countless booty and spoils.”[1245] Another party, under Gilbert de Gant and Robert de Ropesley, had been charged by Louis to check the excursions whereby the baronial castles in the neighbourhood of Nottingham and Newark were being reduced to ashes, and the baronial lands around them to subjection, by the garrisons of those two royal fortresses. Gilbert and Robert took the city of Lincoln and laid a tax on the whole of Lindsey; but Lincoln castle was too strong for them, so they went on to invade Holland, which they ravaged and likewise placed under tribute. A third body of troops under Robert de Ros, Peter de Brus and Richard de Percy was meanwhile conquering Yorkshire for Louis;[1246] and Alexander of Scotland had again set out “with all his host, except the Scots from whom he took money,” to renew the siege of Carlisle.[1247] This, like all other sieges of that famous fortress, proved a long and wearisome business; Alexander, however, relieved its tediousness by expeditions into the counties of Northumberland and Durham. He had no purpose now of conquering them for himself; his aim was simply to join hands with the other invader. The Scot king was the natural ally of the English king’s adversary. Thus by the end of July the power of Louis extended from the Channel to the Scottish border, but not without some important breaks. The castles of the bishopric of Durham were still held for John by Hugh de Balliol and Philip de Ulecotes.[1248] The stranger’s hold upon the south coast was precarious in the extreme so long as Dover, the “key of England,” defied him under Hubert de Burgh; and Windsor at once threatened his hold upon London, and barred his way to the Midlands and the West. These were the districts in which John counted upon making good his defence. Throughout June, while Louis was in Hampshire, John was perambulating Wiltshire and Dorset, personally seeing to the fortification and replenishing of the fortresses in those two shires, planning schemes and giving orders for the security of the royal castles in all parts of his realm, and issuing instructions to their custodians how to act in every possible contingency.[1249] Diplomacy went hand in hand with military precautions. Overtures were made to Reginald de Braose, the deadliest of John’s personal foes, and one of those who had most influence on the western border, for his return to allegiance at the price of the restoration of his heritage.[1250] Safe-conducts were offered to “all who might choose to return to the king’s service” through the intervention of certain appointed persons.[1251] A temporary submission to the invader’s demand of “tenserie” was formally sanctioned in special cases where it was