Pirate,
Wrong is wrong, if you let him get away with it, it could get worse later. A week ago, I had to meet with the State Attorney for a mediation hearing about a neighbor dispute. I had no idea what it was about until I called down town and found out. . Come to find out my neighbor assumed my fence was on his property and he wanted justice. I went prepared with pictures and survey which was senior over his, One of my fences is about 4.7 ft from the property line, and he assumed his corner was at my fence corner. Not so. The distance from my corner to the capped pin with number is noted. I up scaled that corner about 5 times , and after looking at it for several minutes, his only words were, I will have a new survey done, and Friday, they were out there doing their thing, and I should know the results in a week. I feel certain I did no wrong. by putting a fence inside my side the line on the survey. My survey is the large survey for 40 acres, and his is for ten acres of the 40 acres parcel. Just ask several surveyors in your area about the time line thing. You can't assume that a fence line or a tree line is the property line. He is not a good neighbor if he doesn't understand right is right.
But sir . your bull has been fertilizing my cows for years, don't that make him mine.