Sri Krishna Devaraya, the legendary ruler of the Vijayanagara Empire is well known to us. Although his native tongue was Tulu, he was widely known as Andhra Bhoja, due to the tremendous efforts he made to ensure the spread of the Telugu language! It is only prudent to be curious as to why a Non-Telugu ruler strove so much for Telugu. Once this thought got inside my head, I couldn't rest until I found out. After digging deep on Quora, I found a question thread which lead me towards a fairly satisfactory explanation.
This is the origins story of the 'Amuktamalyada'. As the story goes, Emperor Sri Krishnadevaraya was traveling through Vijayawada during his Kalinga campaign. He had conquered Vijayawada, Kondapalli fort and the surrounding areas. He came to know about the holy temple of Andhra Viṣhṇu and visited Srikakulam village for a few days. He performed the Ekadasi Vratham during that time. It is here that Andhra Viṣhṇu appeared to the emperor in an early morning dream. Krishnadevaraya said observing the fast of the Vishnu's Day, in the fourth and last watch of that God's night, Andhra Vishnu came to him in a dream. Andhra Viṣhṇu told him to compose the story of his wedding with Andal at Srirangam. He also ordered the emperor to tell the story in the Telugu language. The emperor obliged, composing Amuktamalyada which is one of the most famous poetic works in Telugu Literature.
From the 14th poem of this exemplary work we can see that the Lord Śrī Āndhra Viṣhṇu refers himself as King of Telugus (Telugu Vallabhunḍa) and refers Sri Krishnadevaraya as Kannada King (Kannaḍa Rāya).
తెలుఁగ దేల నన్న దేశంబు దెలుఁగేను
తెలుఁగు వల్లభుండఁ దెలుఁ గొకండ
యెల్ల నృపులగొలువ నెరుఁగ వే బాసాడి
దేశభాషలందుఁ తెలుఁగు లెస్స
— శ్రీ ఆంధ్ర విష్ణు
Meaning of Quote:"If you ask why a work in Telugu; I am Telugu (i.e., belong to Telugu land) and King of Telugus. Telugu allows use of "Kandham's". So, with all kings serving under you, by speaking Telugu you will know that of all regional languages Telugu is superior.
Sri Krishna devaraya took the words of god to heart and strove hard to spread the greatness of Telugu far and wide. The 'Amuktamalyada' is a testament not only to Sri Krishna Devaraya's mastery of the Telugu Language, but also to the wonderful language that Telugu is.