Complex sentence: On 7 March Metternich was wakened by the news that Napoleon had absconded from his island prison of Elba and within an hour he had met with both the Tsar and the King of Prussia.
Split into simpler sentences: On 7 March Metternich was wakened by news that Napoleon had absconded from his island prison of Elba. Within an hour he had met with both the Tsar and the King of Prussia.