These days most caravans are fitted with the anti-skid thingies on the hitch, which keeps them smoothly in line.
Scariest moment I ever had with a trailer was taking one big beast to the mart. We had left him too much room to move around and he decided to wander about. Ex-BH was driving, his big Mitsubishi Animal, so a very powerful tow vehicle. He kept his cool but at he point he simply said, "I am not steering this car, the trailer is."
We were lucky there was no traffic coming towards us so our weaving across the road caused no harm (except to our hearts!)
So I always take trailer safety seriously, check towing weights, get the weight distribution right, etc. A
One eye-opener, since I bought an unbraked sheep trailer, has been the unbraked towing weights of the various cars. We have only one vehicle can tow it legally with 3 big pigs or 7 large sheep on board. And the most powerful towing car (aside from the Mitsubishi we now thankfully have on site) when the trailer is braked is the least capable when towing unbraked. Everyone thinks I'm a terrible fussbudget, but there's an extremely steep hill down to our abattoir, you don't want to find your brakes can't stop the combined weight of your car, the trailer and the livestock...