Samurai Warriors 2 4th and 5th weapons guide: Ginchiyo's 4th at the Conquest of Kyushu part 2

Information taken straight from Rampidzier's guide on gamefaqs, Requirements: Force Iehisa Shimazu, Yoshihiro Shimazu, and Toshihisa Shimazu to retreat and then when they reappear in the southern garrison, defeat them in the following order: Iehisa, Toshihisa, Yoshihiro. I'm pretty sure that you can just kill the three of them that aren't already in the southern garrison and then go and slaughter them, but I'm not entirely sure so I decided to waste all of your time, instead. Because I'm nice.