Newcastle's position had briefly been threatened by Carteret, a royal favourite, but by 1743, Newcastle and his brother were firmly in control of British policy until 1756. Newcastle now set about drawing up a fresh scheme to enhance British power on the continent, including an attempt to persuade the Dutch Republic into the anti-French alliance and mediating the dispute between Austria and Prussia, which led to the Treaty of Dresden in 1745. He also approved plans for a colonial raid against Louisbourg in 1745, which was successful. Along with the defeat of a Spanish Invasion of Georgia in 1742, this strengthened the British position in North America.