According to a later calculated tradition, King שאול and three of his sons died at Gilboa on 28 Elul.

כ״ח באלול ב׳תתפ״ד28th of Elul, AM 2884

Mount Gilboa · ארץ ישראל Ereẓ Yisraʾel

https://thisjewish.day/article/2884-06-28-%C5%9Daul-sons-deaths