After his defeat, Sverre limped back to Bergen. He was soon followed by a numerically superior Bagler army under the leadership of Nikolas Arnesson and Hallvard of Såstad. Sverre continued to hold Bergenhus fortress. This castle proved to be impregnable, giving the Birkebeiners a secure base of operation. The following summer was to be called the "Bergen’s summer" and was dominated by indecisive skirmishing in the Bergen area. On 11 August the Baglers set fire to Bergen. The destruction was complete, even the churches were burnt down. Facing starvation, Sverre slipped away with most of his men to Trøndelag.