Complex sentence: They proved unsuited to this task, because (like many other bombers used by the RAF), they were too vulnerable with no long-range fighter escorts, being replaced in this role by the de Havilland Mosquito.
Split into simpler sentences: They proved unsuited to this task, because (like many other bombers used by the RAF), they were too vulnerable without long-range fighter escorts. They were replaced in this role by the de Havilland Mosquito.