as allied forces converged to fulfill douglas macarthur's promised return, japan implemented operation "shō" to defend the philippines. convoy hi-71 carried imperial japanese army troops, weaponry and supplies from the home islands of japan to reinforce the philippines. the convoy left moji on 8 august 1944 accompanied by the 6th escort group of two destroyers and five "kaibōkan" with an escort carrier embarking the 931st air group detachment of a dozen nakajima b5n "kate" attack planes. as the convoy departed the mako naval base in the pescadores on 17 august, it was reinforced by another destroyer and four "kaibōkan" to counter united states submarines operating in the luzon strait.