The girl king - Meg Clothier

Georgia, 1177.
King Giorgi, who's long defended his fragile kingdom's throne, has no son to succeed him.
When a revolt threatens his daughter Tamar's life, she is sent, disguised as a boy, to live in the mountains, but she's betrayed into the hands of her enemies.
Her courageous escape convinces Giorgi she should be his heir.
However, after he dies she is truly alone.
Facing hostile forces and warring factions at court, she must win the respect of her friends and enemies, and she must marry a man of whom the elders approve.
But her heart belongs to a boy from the mountains.
Meanwhile, rebellion brews at home.
Powerful foes circle her borders - Tamar must decide between the man she loves and the land she adores...