▁clear , ▁the ▁ 3 - p ound er ▁fired ▁another ▁six ▁sh ots ▁into ▁the ▁h ull ▁of ▁U B - 4 ▁at ▁point ▁blank ▁range . ▁All ▁the ▁while ▁small ▁arms ▁fire ▁from ▁In ver ly ons ▁crew ▁pe pper ed ▁the ▁sub marine . ▁The ▁U - bo at ▁began ▁going ▁down ▁by ▁the ▁bow , ▁becoming ▁nearly ▁vertical ▁before ▁disappear ing ▁below ▁the ▁surface . ▁A ▁member ▁of ▁In ver ly ons ▁crew ▁attempted ▁the ▁rescue ▁of ▁one ▁crew man ▁from ▁U B - 4 , ▁but ▁was ▁unable ▁to ▁reach ▁him ▁before ▁he ▁went ▁under , ▁meeting ▁the ▁same ▁fate ▁as ▁the ▁other ▁th ir teen ▁crew men . ▁ ▁As ▁U B - 4 ▁went ▁down , ▁her ▁h ulk ▁fou led ▁the ▁In ver ly ons ▁n ets — which ▁had ▁been ▁deployed ▁to ▁keep ▁up ▁the ▁appearance ▁of ▁a ▁real ▁fish ing ▁boat — ess entially ▁anch oring ▁In ver ly on ▁in ▁place . ▁The ▁Q - ship ' s ▁crew , ▁not ▁having ▁a ▁wireless ▁set ▁on ▁board , ▁sent ▁word ▁of ▁the ▁encounter ▁with ▁another ▁sm ack , ▁and ▁followed ▁up ▁by ▁re le asing ▁mess enger ▁p ige ons ▁the ▁following ▁morning , ▁request ing ▁instructions ▁on ▁what ▁to ▁do ▁with ▁U B - 4 . ▁The ▁thought ▁of ▁salv aging ▁the ▁sn ag ged ▁U - bo at ▁was ▁rejected , ▁so ▁the ▁n ets ▁were ▁cut , ▁free ing ▁U B - 4 ▁to ▁sink ▁to ▁the ▁bottom .