He managed to convince King Frederick III and Queen Joanna I of Naples of the need for a peace agreement, secured by a dynastic marriage between both countries.
At the insistence of Queen Joanna I, clauses were introduced into it that guaranteed that the bride, after marriage, would kept all her rights, including the hereditary ones, and it was stipulated that the maintenance allocated to her by her husband should be the same as that received by all previous consorts of the Kings of Sicily.
And, finally, Antonia's sudden death brought to naught diplomatic efforts to strengthen ties between Messina and Naples, as a result of which the King of Sicily resumed cooperation with Milan.
[3] In the winter of 1375, rebellious vassals led by Enrico II Rosso, Count of Aidone, did not allow the royal galley with King Frederick III and his wife on board to enter the port of Messina.
The royal couple stopped at the port of Reggio di Calabria, where on 19 January of the same year, the same rebels attacked their ship, threatening them with death.