John Philip Holland
"U-4" was built as part of a plan by the Austro-Hungarian Navy to competitively evaluate foreign submarine designs from Simon Lake, Germaniawerft, and John Philip Holland. The Austro-Hungarian Navy authorized the construction of "U-4" (and sister ship, "U-3") in 1906 by Germaniawerft of Kiel, Germany. "U-4" was laid down on 12 March 1907 and launched on 20 November 1908. After completion, she was towed via Gibraltar to Pola, where she arrived on 19 April 1909.