The mother of Gustavus Adolphus was a German princess of superior education for the times. A haughty queen, a strict disciplinarian, thereby developing in her son a quick and ready obedience to the laws of the family. Who would command must first learn to obey. She much preferred her second son, Charles Philip, and, had Gustavus been less generous, or less noble, an unnatural jealousy might have divided the brothers, but the young Duke of Finland, as Gustavus was called, acted as though he thought his mother could do no wrong. Gustavus had three teachers, each of whom left a strong impression upon his character—John Skytte, a man who had spent ten years in travel, Von Mörner, an accomplished, traveled man, and Count de la Gardie, a Swedish noble of a French family, who instructed Gustavus in fencing and in military tactics. Gustavus had an attractive personality and won the abiding affection of his cousin, Duke John, the only one of Sigismund's sons who took the Swedish side of the religious and family quarrel. Duke John married the only sister of Gustavus, Mary Elizabeth, and proved a brother, indeed, after the death of King Charles. For the choice was left to the people and to the Estates as to whether they preferred John or Gustavus. At the sincere urgency of Duke John the young Duke of Finland, Gustavus, was chosen. King Charles IX. began early to train his son in public affairs. When Gustavus was only ten years old his father kept him at his side at all cabinet meetings and in great public assemblies. He encouraged him to talk to officers from foreign countries in their own language. The king permitted him to ask questions on war, special battles and methods of governing, and the father was proud of the eager, precocious child, in whom he recognized a mental and spiritual power far beyond his own. At the age of fourteen he was sent, with his mother, through northern Sweden, in order that he might become acquainted with the people of his own country. The king said, "You are only a boy, but listen to everyone who solicits your protection, help everyone according to your means, and dismiss no one without a word of comfort." The gracious boy made many friends in this early journey, men who afterwards gladly gave life itself to forward his interests. At the age of fifteen he was greatly disappointed because he was not permitted to lead an army against the Russians, but for once his father required him to remain at home to learn affairs concerning the internal and external policy of the Swedish government. But in 1611, at the age of seventeen, when Denmark had declared war against Sweden, he was permitted to command a body of troops. He was sent to deliver the town of Calmar which was besieged by the Danes. He was afterward joined by troops under Duke John and the king himself. On August 16th, 1611, the town and castle were surrendered by a commander who proved to be a renegade Swede whom King Charles had offended.