midnight
The extreme cold had everywhere so completely frozen the sea that there was no difficulty in crossing , which , they learned , was not often the case . Three sledges had been engaged for their transport . The distance was about 120 miles ; but it was broken by the islands of the Aland Archipelago , and upon one or other of these they could take refuge in the event of any sudden change of weather . They were to start at midnight , and would reach Bomarsund , on the main island of Aland , on the following evening , wait there for twenty-four hours to rest the animals , and would reach the mainland the next day . The frost continued unbroken , and they crossed the gulf without difficulty , travelled rapidly across Sweden , and reached England without adventure of any kind . They waited for a day in London . Frank carried despatches from Sir Robert Wilson , and was occupied at the War Office all day , having a very long interview with the minister , to whom he gave a much more detailed account of the campaign than had been given in the general 's reports .