During the first weeks of the war, some of his acquaintances were killed in the violence, and his brother, the psychiatrist Christian Sibelius, was arrested as he refused to reserve beds for the Red soldiers who had suffered shell shock at the front.
I løbet af krigens første uger blev nogle af hans bekendte dræbt i volden, og hans broder, psykiater Christian Sibelius, blev anholdt, da han nægtede at reservere senge til de røde soldater, der havde lidt under granatchock ved fronten.