With my semi wild mare I had to walk her down before I could reliably catch her, and is as simple as it sounds, go out, start to walk up to him, if he walks away just quietly follow him, if he runs, just keep walking after him, try not to let him stop or eat, just keep gentle pressure on him and keep him moving.
Eventually, and it can take HOURS, he will get so fed up he will stand still, then you just walk up pet him and walk away.
Next day, or later on the same day, do it again, the number of repeats depends on him
Horses always get bored with this game and figure if they are going to get caught anyway, then it may as well be sooner than later. Obviously a smaller area would work a lot better, it saves you a lot of walking, but it can be done in a larger area.
Took quite a while with Bert, she was aggressive as well so when she got bored with walking away, she would revert to trying to chase me off instead, now that is very frustrating, having to chase away a horse that you are trying to catch LOL