The Icemark Chronicles

When her father dies in battle, 14-year-old Thirrin becomes Queen of the Icemark. Not only must she win the respect of her people, but she has to raise an army to protect them from the most formidable threat of invasion her nation has ever known.

After the death of her beloved father, headstrong princess Thirrin Freer Strong-In-The-Arm becomes warrior queen of her homeland, Icemark, defending it from a formidable invader. Despite Thirrin's bravery and the support of Oskan, the Witch's son, the task proves more difficult than Thirrin ever dreamed. She must assemble a force to rival her opponent. And, in the chill winter of Icemark, she only has until spring to unite the strange beasts and frightening creatures who live just outside her country.

Seventeen years have passed since the tiny kingdom of the Icemark last defended itself from invasion. Now Thirrin and Oskan have five children, but Scipio Bellorum has a family too - and he is back with his sons and a fleet of sky ships to finish what he started.