YOU SAID:
He has acted against the benefit of our alliance!
INTO JAPANESE
彼は私たちの同盟の利益に反して行動しました!
BACK INTO ENGLISH
He acted against the interests of our alliance!
INTO JAPANESE
彼は私たちの同盟の利益に反して行動しました!
BACK INTO ENGLISH
He acted against the interests of our alliance!
That didn't even make that much sense in English.