Steel Tiger
Senior Master
I don't suppose you know about Varous? The Roman General who lost Romes three best Legions to the Germans? It fits with what you mentioned about 'assume the population is largely neutral/freindly'. It shows why that is a bad idea!
Would that be Publius Quinctilius Varus you're referring to? The whole Teutoburg Forest campaign is a very good example of failing to understand the temperament of the local population.