▁broken ▁into ▁sections ▁and ▁sh ipped ▁by ▁rail ▁to ▁Ant werp ▁for ▁re assembly . ▁She ▁was ▁launched ▁and ▁commission ed ▁as ▁SM ▁U B - 4 ▁in ▁March ▁ 1 9 1 5 . ▁ ▁U B - 4 ▁conducted ▁the ▁first ▁sortie ▁of ▁the ▁Fland ers ▁Fl ot illa ▁in ▁April , ▁during ▁which ▁she ▁s ank ▁the ▁Belg ian ▁Rel ief ▁ship ▁, ▁the ▁first ▁ship ▁cred ited ▁to ▁the ▁fl ot illa . ▁She ▁s ank ▁three ▁more ▁ships ▁from ▁mid - A pril ▁to ▁mid - August . ▁On ▁ 1 5 ▁August , ▁U B - 4 ▁sur fac ed ▁near ▁the ▁British ▁Q - ship ▁ ▁and ▁was ▁s unk ▁by ▁gun fire ▁from ▁the ▁sail ing ▁vessel . ▁None ▁of ▁U B - 4 s ▁ 1 4 ▁crew men ▁surv ived ▁the ▁attack . ▁ ▁Design ▁and ▁construction ▁ ▁After ▁the ▁German ▁Army ' s ▁rapid ▁advance ▁along ▁the ▁North ▁Sea ▁coast ▁in ▁the ▁earliest ▁stages ▁of ▁World ▁War ▁I , ▁the ▁German ▁Imperial ▁Navy ▁found ▁itself ▁without ▁suitable ▁sub mar ines ▁that ▁could ▁be ▁operated ▁in ▁the ▁narrow ▁and ▁shall ow ▁environment ▁off ▁Fland ers . ▁Project ▁ 3 4 , ▁a ▁design ▁effort ▁begun ▁in ▁mid - August ▁ 1 9 1 4 , ▁produced ▁the ▁Type ▁U B ▁I ▁design : ▁a ▁small ▁sub marine ▁that ▁could ▁be ▁sh ipped ▁by ▁rail ▁to ▁a ▁port ▁of ▁operations ▁and ▁quickly ▁assemble d . ▁Con stra ined ▁by ▁rail road ▁size ▁limitations ,