On 16 December 1916, four under construction in the Reiherstieg and Flensburger Schiffbau yards were taken over by the navy and converted to military specification as Type U 151 U-boats, being designated U-151 to U-154. The remaining two, along with Deutschland, which became U-155, passed into naval control in February 1917, as U-156 and U-157.[2]