1546 [age one] Born the first son of Mogami Yoshimori, Lord of Yamagata Castle. He was called Hakujūmaru as a child.
1558 [age 13] Celebrated the rite to mark his attainment of manhood, and receiving the right to use the character "Yoshi" [ 義 ] from the Shogun Ashikaga Yoshiteru he took the name "Yoshiaki" [ 義光 ] .
1570[age 25] Succeeded to the head of the Mogami clan. Counting from Shiba Kaneyori, he became the 11th Lord of Yamagata Castle.
1600 [age 55] Battle of Keichō Dewa / Naoe Kanetsugu's Uesugi forces attack Yamagata. Fierce fighting at Hasedo, Kaminoyama and other places in Yamagata Prefecture.
1602 [age 57] Became a great daimyo with land holdings which produced 570 thousand koku [135 million liters] of rice. His was the fifth largest domain, outside of Tokugawa Toyotomi's clan. At this time Yamagata was completely laid out as a fully equipped castle town.
1611 [age 66] Took a high ranking position in the Guards, Jyushii Konoe-no-shōshō. Brought the Shōnai Plain under cultivation by building irrigation systems at Kitadateseki and Inabazeki.
1614 [age 69] Died of illness in Yamagata Castle on January 18. Was buried at Kōzenji in Yamagata City.
