This reminds me of a family anecdote. My great-uncle was a French officer in Indochina and, through fuzzy circumstances to do with his previous service, learnt to speak a few of the local dialects, although this was not widely known.
At the negotiating table with a leader from a neutral local faction, his interpreter, who was sympathetic to the enemy, was changing the meaning of everything said to make the negotiations fail. After letting the charade go on for a while, great-uncle spoke up in the local dialect to the great surprise of both the interpreter and the other party, which resulted in one less living interpreter and one more alliance for the French.
At the negotiating table with a leader from a neutral local faction, his interpreter, who was sympathetic to the enemy, was changing the meaning of everything said to make the negotiations fail. After letting the charade go on for a while, great-uncle spoke up in the local dialect to the great surprise of both the interpreter and the other party, which resulted in one less living interpreter and one more alliance for the French.