If the track is accurate, it's amazing what detail there is. This path in green displays a horseman's "discussion" with a horse not wanting to go forward to an obstacle, like a riverbank:
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The pair wasn't blown into the river if you asked me. The horse was asked repeatedly until it responded by stepping or leaping in. The leap could have unseated RM and things snowballed from there?
This is the exact pattern a novice horse will take when introducing it to a ditch crossing or water obstacle.