session in the Storting. But he refused to surrender the Norwegian border forts to Swedish troops. On 15 July the four-power delegation rejected Christian Frederick's proposal that Norway's constitution form the basis for negotiations about a union with Sweden but promised to put the proposal to the Swedish king for consideration. The negotiations were a partial success in that the delegation left convinced that Christian Frederick was sincere and had the backing of a popular movement. On 20 July Bernadotte sent a letter to his "cousin" Christian Frederick accusing him of intrigues and foolhardy adventurism. To add to the problems, the three Norwegians who had made their way to London were arrested, charged with carrying false passports and papers. They were deported immediately. On 22 July Bernadotte met with the delegation that had been in Norway. They encouraged him to consider Christian Frederick's proposed terms for a union with Sweden, but the crown prince was outraged. He reiterated his ultimatum that Christian Frederick either relinquish all rights to the throne and abandon the border posts or face war. On 27 July a Swedish naval fleet took over Hvaler, effectively putting Sweden at war with Norway. The day after, Christian Frederick rejected the Swedish ultimatum, saying that such a surrender would constitute treason against the Norwegian people. On 29 July Swedish forces moved to invade Norway. Swedish-Norwegian War Swedish forces met with little resistance as they advanced northward into Norway, bypassing the fortress of Fredriksten. The first hostilities were short and ended with decisive victories for Sweden. By 4 August the fortified city of Fredrikstad surrendered. Christian Frederick ordered a retreat to the river Glomma. The Swedish Army, trying to intercept the retreat, was stopped at the battle of Langnes, an important tactical victory by the Norwegians. The Swedish assaults from the east were effectively resisted near Kongsvinger. On 3 August Christian Frederick announced his political will in a cabinet meeting in Moss. On 7 August a delegation from Bernadotte arrived at the Norwegian military headquarters in Spydeberg with a cease-fire offer that would join Norway in a union with Sweden and respect the Norwegian constitution. The day after, Christian Frederick expressed himself in favor of the terms, allowing Swedish troops to remain in positions east of Glomma. Hostilities broke out at Glomma, resulting in casualties, but the Norwegian forces were ordered to retreat. Peace negotiations with Swedish envoys began in