Stephen had waited until Robert had left England, and then, emerging from his sick room, had pounced down upon Wareham, the strong castle which the earl had entrusted to his son, had taken it, and then hastening northwards, had burnt the town of Oxford, and shut up the empress in the castle. There she remained until her brother could succor her. He returned at once, recovered Wareham and some castles in Dorset, and called together the forces of his party at Cirencester. But the winter was now advancing; the empress contrived a romantic escape in the snow from Oxford, and before active war could be resumed she directed that the castle should be surrendered. So the year 1142 comes to an end, and we see the two parties resting in their exhaustion. The western shires acknowledged Matilda, who reigned at Gloucester; the eastern acknowledged Stephen, who made Kent his head quarters. The midland counties were the seat of languid warfare, partly carried on about Oxford, which was a central debating ground between the two competitors, partly in Lincolnshire and Essex, where Stephen had to keep in order those great nobles who aimed at independence. Geoffrey de Mandeville, the earl of Essex, who accepted his earldom from both the courts, employed him chiefly in 1143 and 1144. The earl of Chester, who was uniformly opposed to Stephen, but who no doubt fought for himself far more than for the empress, held Lincoln as a constant thorn in the royal side. In 1145 Oxfordshire and Berkshire were the seat of war; in 1146 Stephen surprised the earl of Chester at Northampton and compelled him to give up Lincoln, and now for the first time seems to have thought himself a king. In despite of all precedent and all prejudice, defying a superstition to which even Henry II. thought it wise to bow, that no king should wear his crown within the walls of Lincoln, he wore his crown there on Christmas Day. [Sidenote: Period of anarchy. ]