It is said that Shingen expelled his father and misled his enemies by using tricks (not that Shingen's actions were especially strange considering it was the Sengoku period (warlike period)), but Kenshin was furious as it was contrary to his morals.
信玄が父親を追放したり、謀略を駆使して敵を貶めたりするのは謙信に言わせるところの道徳観に反しており（もっとも、戦国という時代を考えれば、信玄の行いは別にあってもおかしくないものだが）、謙信は信玄の行いに激怒したという。