|Shipyard||Kaiserliche Werft, Danzig|
|Ordered||27 May 1916|
|Launched||12 Jan 1917|
|Commissioned||26 Mar 1918|
There was another U 138 in World War Two
That boat was launched from its shipyard on 18 May 1940 and commissioned into the Kriegsmarine on 27 Jun 1940. Take a look at U 138 from WWII.