In the Siege of Odawara to suppress the Go-Hojo ('Go' means 'Late') clan (in 1590), Toshiie invaded Kozuke Province as a Commander in Chief of the north provinces forces with Kagekatsu UESUGI and Masayuki SANADA, and captured Kozuke Matsuida-jo Castle which was the northernmost key position for the Hojo clan, and then defeated the other castles one after another as well.
（1590年）の後北条氏制圧のための小田原の役では北国勢の総指揮として上杉景勝、真田昌幸と共に上野に入り、北条氏の北端要所の上野松井田城を攻略、他の諸城も次々と攻略した。