Complex sentence: The "Oryol" mistook the "Shinano Maru" for another Russian vessel and did not attempt to notify the fleet--instead, she signaled to inform the Japanese ship that there were other Russian vessels nearby.
Split into simpler sentences: The "Oryol" mistook the "Shinano Maru" for another Russian vessel and did not attempt to notify the fleet. Instead, she signaled to inform the Japanese ship that there were other Russian vessels nearby.