Please answer the following question: I know that the answer to the question "What caused the three great powers to take such drastic action?" is in "After years of negotiation, three Great Powers, Russia, the United Kingdom and France, decided to intervene in the conflict and each nation sent a navy to Greece. Following news that combined Ottoman–Egyptian fleets were going to attack the Greek island of Hydra, the allied fleet intercepted the Ottoman–Egyptian fleet at Navarino. After a week-long standoff, a battle began which resulted in the destruction of the Ottoman–Egyptian fleet. A French expeditionary force was dispatched to supervise the evacuation of the Egyptian army from the Peloponnese, while the Greeks proceeded to the captured part of Central Greece by 1828. As a result of years of negotiation, the nascent Greek state was finally recognized under the London Protocol in 1830.". Can you tell me what it is?
A:
news that combined Ottoman–Egyptian fleets were going to attack the Greek island of Hydra