It took me a couple of months, but I turned them into Reagan supporters. The deal was closed on Inauguration Day, when Iran released the hostages.
I had been in country almost 4 years, and my German was pretty good by then. It was good enough to get quizzical looks from folks..."he looks like a GI, but he's speaking German, and without an accent." lol
O/T, I'm a huge supporter of immersion training. That's how I learned German, first by living off post. Later, I took a couple of immersion courses on base, and it took off from there. Shortly after completing the second course, I spent a summer at a German anti-aircraft range, as XO of a detachment formed to support American units training there. We were the only Americans for 200 miles...it was awesome!
After my first meeting with the Base Commander, he pulled me aside and said, "you can ditch your interpreter."
I know a little German....