Brownsea, also known as Branksea or Bruno's Island, is the largest of the eight named islands in Poole Harbour.
Brownsea is known the world over as the birthplace of the Scouting movement, for it was here in 1907 that Lord Baden-Powell held the first Boy Scout camp on the northern end of the island. It may be that the scouting ideal of a good deed each day came from the hermit monk, who, some 1400 years earlier lit a beacon at night to guide sailors into the harbour.
The island was fortified by Henry VIII who built a square blockhouse on Brownsea to guard the entrance to Poole harbour. Originally a square single story building with walls 40 feet long and 9 feet thick, it had a moat on three sides and a hexagonal gun platform on the fourth seaward facing side. During the Civil War it was held for Parliament and was suitably reinforced.
William Benson [1682-1754] moved into Branksea Castle on Brownsea Island, in about 1710. He then created a national stir with his Letter to Sir Jacob Banks  which argued that kings were accountable only to God. It sold 100,000 copies. Frederick, Prince of Wales, was among his visitors to Brownsea Island. He was a popular heir apparent but he would never take the throne as he failed to outlive his unpopular father. Benson's life was also sliding into obscurity and after a serious mental illness in 1741 his former love of books had turned into hatred and he was known as 'Mad Benson',
The Island was bought by Sir Augustus Foster [1780-1848] in 1840. His claim to fame was as the last man to put Britain in a state of war with the United States of America. As the British Minister Plenipotentiary in Washington, from August 1811, he failed to sort out a simmering row over the impressment of American seamen into the Royal Navy for the war against France. This compromised American neutrality.
Matters came to a head in 1812 but in reality there was no longer any dispute, because London had already withdrawn the contentious orders, on 16th June. Unaware of this, on the 18th, the Americans declared war on the British - and prepared to invade Canada.
That offensive was out maneuvered and British troops in North America marched south to burn the Capitol in 1813 and destroy most of the Library of Congress. Foster had to do the diplomatic thing and pack his bags.
America eventually won the war, in 1815 in New Orleans, and Foster went on to Denmark and Turin. Retirement to Brownsea, or Branksea Castle as the mansion was known, coincided with failing health and deep bouts of depression. He slit his throat, at his castle home, on 1st August 1848.
In 1853 a Colonel Waugh went bankrupt mining china clay which proved to be worthless. It was this same Colonel who lavished £10,000 on the beautiful church, a not inconsiderable sum in the 1850's.
On Sunday 26th January 1896 a fire swept through the castle, the newly installed electricity widely considered to be the cause. Whatever started the blaze the outcome was the building that stands today, for during the rebuilding several turrets and other features were removed.
Brownsea has something of a reputation for the eccentricity of it's owners, probably the most interesting of whom was the recluse Mrs. Bonham Christie who kept the island as a bird sanctuary where callers were definitely not welcome. In fact during the 1930's, to quote the National Trust guide, she employed 'a blonde and powerful female Scandinavian PT instructor to throw visitors off the island'.
Today Brownsea is under the control of The National Trust and visitors are decidedly welcome. It is one of the last remaining outposts of the red squirrel in southern England and the sound of peacocks echoes though the woods.