In the twelfth year of the life of Paul Atreides, the Duke finally decided to make commit to a marriage to cement the friendship between House Atreides and House Ecaz, marriage to Armand's daughter, Ilesa. Although the Duke had already announced to the Imperium that Paul was his intended heir, there was still coolness to the idea of marriage from Leto's concubine, Jessica Atreides. When Ilesa arranged to travel Cala City in the days prior to her upcoming nuptials to Leto, Jessica decided for the sake of everyone involved to strike up a friendship with Ilesa.
During the wedding ceremony a few days later at Castle Caladan; House Moritani, enemy of House Ecaz, began the War of Assassins of 10,187 AG by cleverly disguising hexagonal blades on the sides of potted plants at the ceremony. As the Wedding March began to play, the sharply bladed discs began circling through the air, trying to strike their intended Ecazian targets, Armand and Ilesa. Rivvy Dinari, personal bodyguard to the Archduke, was able to keep the intended discs from killing Armand, by placing his own body in their paths. One was deflected, and the other sliced off the Archduke's lower, left arm.
The other circling disc was able to get past Ilesa's personal bodyguard, Whitmore Bludd, as he was only able to deflect one, and hesitated for a half second, allowing the other to slice Ilesa's cartoid artery. Ilesa grabbed at her neck trying to stop the flow of blood, but was unable to, and she bled to death.
It was at Ilesa's funeral that Leto began plotting revenge with the Archduke against House Moritani.