Page "Charles I of England" Paragraph 7

Charles was not as valued as his physically stronger, elder brother, Henry, Prince of Wales, whom Charles personally adored and attempted to emulate.

In 1605, Charles was created Duke of York, which is customary in the case of the sovereign's second son.

However, when Henry died of suspected typhoid ( or possibly porphyria ) at the age of 18 in 1612, two weeks before Charles's 12th birthday, Charles became heir apparent.

As the eldest living son of the sovereign, Charles automatically gained several titles ( including Duke of Cornwall and Duke of Rothesay ), and subsequently was created Prince of Wales and Earl of Chester in November 1616.