That's how I see it. If I was in his position, I would have left a note as well. Hopefully you all can work it out, as it's a misunderstanding more than likely. A phone call explaining the situation, and an apology would likely solve things.

The title of the post should be how to be a rude neighbor. If this is the landowner you need to call him asap and apologize and have your FIL call depending in how you are received.
Look at it from his angle. He gets a request to use his gate and roads for your convenience. Then when he meets your people you are unloading atv on his land and riding around his property lines and gate. I would not have left a note. I would have been waiting for FIL to return so I could explain that ! He is a guest while he is on the wrong side of the property line using my roads that I own and driving around my gate and property line.
Please don't take this the wrong way, look at it from his angle.

Lefthorn, based off those deer pics you posted, put on your biggest smile and go along to get along!

I dont see how your FIL is coming off as being the rude one.. seems to me that if its a shared access road, then the other guy wouldnt be rude by blocking the road to get to your property therefore eliminating the need for FIL to unload on his property to access yours.. 2 can play that game and if hes not understanding, then i would return the favor and block the road so he cant access his property on the other side of you

No. No. No. No.

Why do folks insist on revenge when it only serves to go against their own interests? It is literally irrational. It makes zero sense.

Hmmm wonder if it's the landowner who doesn't allow atvs or the lease holder.

I wasnt insisting on revenge.. i would much rather be cordial and on good terms, especially when you both have interests on a shared access road. Its inevitable that you are going to be seeing each other again, but some people are just hard to deal with... we've all dealt with that one person who will go out of his or her way to make things difficult for you just out of spite. Sometimes you have to give people a dose of their own medicine

Sounds like your FIL needs to write down the combo number or better yet get a lock with a key and put it on his truck key ring. If he or you already have a master lock key for something else, you can buy a re-keyable lock that a locksmith can key to the same lock. That is what we use so 1 key will open anything on our property. Got tired of flipping thru a giant ring of keys while standing in the rain...

I lease a tract south of Aliceville that has 8 locks on the gate. 4 are separate landowners on that road, 1 is Alabama power, and 3 different groups that hunt off that road.

Well, phone call seemed to go good. I explained what went on and he said "I wondered if that was what happened but thought he would have a combination". He was off one number. Plan to meet him next time I am down there.

I figure it is best for both of us if we can get along

Fil was wrong for driving around gate. Smooth it over or you'll be miserable from now on. Playing nice is the hard part, being an ass is easy. Time for that later, if it comes to it.

Yes, I agree. He was "locked in" and had the combo off by one number. It looked bad and I apologized for him doing that and explained why he did it. Guy was cool about it. I explained that I wanted to be good neighbors, and I figured it would be in the best interest for both of us since we will cross paths at certain times

Good deal, lefthorn. Confronting problems dead on is almost always best.