A major union military victory
Abraham Lincoln really wanted the people to unite together as one, so he wanted the union to come together in success by victory.
It allowed them fewer ships than the US and Britain limiting the kind of parity they hoped to have on the world stage in terms of naval power.
One of the arguments went that the US and Britain had to have larger navies because of their need to maintain a force in more than one operating theater while the Japanese only had to worry about their side of the Pacific. It wasn't something that made a number of hardcore military types within the Japanese leadership very happy, but they ended up signing the treaty anyway (though refused to renew it in the 1930s).
This is called the frustration of purpose. It's a doctrine about how cases would be solved if unforeseen circumstances were to occur. A modern example would be if you took a mortgage but an earthquake completely destroyed your house. Due to the frustration of purpose, you could have your mortgage canceled because you don't have a house that the mortgage was for, so you wouldn't have to pay for it any more.
