Zhang Guan's regency was a dictatorial one, and he suspected people of conspiring against him.
Song Hun heard this and started an uprising, declaring that Zhang Guan had committed treason and that he had authorization from Zhang Xuanjing's grandmother Princess Dowager Ma to kill him.
Their forces battled inside the city, but Song Hun's forces prevailed, and Zhang Guan and Zhang Ju committed suicide.
Song Hun was considered an able and tolerant regent—even, for example, commissioning one of Zhang Guan's bodyguards, Xuan Lu (玄臚), who had, during the battle, tried to kill him with a spear but failed and was captured, as a trusted officer.
In 361, Song Hun grew ill, and Zhang Xuanjing and Princess Dowager Ma visited him personally, asking whether his son Song Linzong (宋林宗) should succeed him if he died.