after germany's conquest of romania (see "romania during world war i"), the german imperial navy had sufficient fuel oil for submarines located in the black sea. "ub-46" and three of her sister ships in the pola flotilla were ordered to constantinople and, en route, had to navigate through the dardanelles, which had been heavily mined by the allies in the middle of 1916. "ub-46" joined the constantinople flotilla () on 7 october.