▁of ▁Cor fu . ▁ ▁Italy ▁signed ▁the ▁Tre aty ▁of ▁London ▁on ▁ 2 6 ▁April ▁ 1 9 1 5 , ▁agree ing ▁to ▁declare ▁war ▁on ▁Aust ro - H ung ary . ▁Bou é ▁de ▁La pe yr ère , ▁concerned ▁about ▁a ▁possible ▁pre - empt ive ▁attack ▁on ▁the ▁southern ▁Italian ▁ports , ▁tempor arily ▁moved ▁all ▁of ▁his ▁arm ored ▁cru is ers , ▁including ▁the ▁three ▁sister s , ▁closer ▁to ▁the ▁Stra it ▁of ▁O tr anto ▁that ▁day . ▁Lé on ▁G amb etta ▁was ▁tor ped o ed ▁and ▁s unk ▁by ▁U - 5 ▁with ▁heavy ▁loss ▁of ▁life ▁on ▁the ▁ 2 7 th . ▁After ▁the ▁s inking , ▁Bou é ▁de ▁La pe yr ère ▁with d rew ▁his ▁arm ored ▁cru is ers ▁even ▁further ▁south ▁to ▁a ▁pat rol ▁line ▁running ▁through ▁the ▁Ger og omb os ▁l ighth ouse ▁on ▁the ▁island ▁of ▁Ce phal onia . ▁He ▁also ▁ordered ▁that ▁pat rol s ▁should ▁be ▁made ▁a ▁speed ▁of ▁, ▁not ▁the ▁le is ure ly ▁ ▁used ▁by ▁Lé on ▁G amb ett as ▁late ▁captain . ▁After ▁the ▁Italian ▁declaration ▁of ▁war ▁on ▁ 2 3 ▁May , ▁the ▁French ▁ships ▁with d rew ▁further ▁into ▁the ▁Mediter rane an ▁and ▁I onian ▁Se as ▁with ▁the ▁ 2 nd ▁D L ▁ultimately ▁bas ing ▁itself ▁at ▁Alexand ria , ▁Egypt , ▁B izer te , ▁French ▁Tun is ia , ▁and