Vexatious questions still remained to be settled. The spoliation claims which were to have been adjusted by the convention of 1802 were finally left to a commission, the United States agreeing to assume all obligations to an amount not exceeding five million dollars. De Onis demurred at stating this amount in the treaty: he would be blamed for having betrayed the honor of Spain by selling the Floridas for a paltry five millions. To which Adams replied dryly that he ought to boast of his bargain instead of being ashamed of it, since it was notorious that the Floridas had always been a burden to the Spanish exchequer. Negotiations came to a standstill again when Adams insisted that certain royal grants of land in the Floridas should be declared null and void. He feared, and not without reason, that these grants would deprive the United States of the domain which was to be used to pay the indemnities assumed in the treaty. De Onis resented the demand as "offensive to the dignity and imprescriptible rights of the Crown of Spain"; and once again Neuville came to the rescue of the treaty and persuaded both parties to agree to a compromise. On the understanding that the royal grants in question had been made subsequent to January 24, 1818, Adams agreed that all grants made since that date (when the first proposal was made by His Majesty for the cession of the Floridas) should be declared null and void; and that all grants made before that date should be confirmed.
On the anniversary of Washington's birthday, De Onis and Adams signed the treaty which carried the United States to its natural limits on the southeast. The event seemed to Adams to mark "a great epocha in our history." "It was near one in the morning," he recorded in his diary, "when I closed the day with ejaculations of fervent gratitude to the Giver of all good. It was, perhaps, the most important day of my life.... Let no idle and unfounded exultation take possession of my mind, as if I would ascribe to my own foresight or exertions any portion of the event." But misgivings followed hard on these joyous reflections. The treaty had still to be ratified, and the disposition of the Spanish Cortes was uncertain. There was, too, considerable opposition in the Senate. "A watchful eye, a resolute purpose, a calm and patient temper, and a favoring Providence will all be as indispensable for the future as they have been for the past in the management of this negotiation," Adams reminded himself. He had need of all these qualities in the trying months that followed.