On 8 June 1918 Horthy took his flagship, "Viribus Unitis", and "Prinz Eugen" south with the lead elements of his fleet. On the evening of 9 June, "Szent István" and "Tegetthoff" followed along with their own escort ships. Horthy's plan called for and to engage the Barrage with the support of the "Tátra"-class destroyers. Meanwhile, "Admiral Spaun" and would be escorted by the fleet's four torpedo boats to Otranto to bombard Italian air and naval stations. The German and Austro-Hungarian submarines would be sent to Valona and Brindisi to ambush Italian, French, British, and American warships that sailed out to engage the Austro-Hungarian fleet, while seaplanes from Cattaro would provide air support and screen the ships' advance. The battleships, and in particular the "Tegetthoff"s, would use their firepower to destroy the Barrage and engage any Allied warships they ran across. Horthy hoped that the inclusion of these ships would prove to be critical in securing a decisive victory.