in opposition to; against
Fixed expression used when someone takes a stance or acts in opposition to another person or group. Often appears as 〜を向こうに回して.
He is fighting against a large corporation.
She stuck to her beliefs in opposition to public opinion.
From 向こう (the other side, opponent) + に + 回す (to turn, to direct), literally 'turning something to the other side'. The expression is used idiomatically to mean confronting or opposing someone.