In this desperate strait Sverre's true greatness revealed itself. He had been accustomed to fight against heavy odds, and the sense of danger served to bring all his energies into play. With undaunted resolution he set to work to repair his losses and to equip himself once more to meet his foes. His first task was to build a fleet instead of the one which the Baglers had destroyed; for without ships he would have been at their mercy. The Trönders whom he called upon for help assisted him faithfully; and by the beginning of spring (1199) he had eight large galleys ready to be launched. Besides these he expected a number of others which the peasants were building for him throughout Tröndelag. The city of Nidaros he fortified with a large new block-house, and built hurling-machines which were used for throwing stones at the enemy. Early in June the Baglers appeared in the fjord with a large fleet, and the usual skirmishing commenced. All their efforts to capture the city were, however, unavailing, and in the battle at Strindsö (June, 1199) their great fleet, which had formerly given them an advantage over the Birchlegs, fell into Sverre's hands. The battle was stubbornly contested, and both parties were wrought up to a warlike fury which refused to give or to take quarter. The king, whose gentleness and humane sentiments had made his stern resolution and courage the more admirable, put here a blot upon his fair name. He yielded to the importunities of his men, and allowed them to avenge the death of their kinsman upon the prisoners. It is but fair to ascribe this single act of cruelty to the momentary ferment of his blood and the hate that flared up uncontrollably against the authors of all his misfortunes.