Complex sentence: She received a commendation for her bravery in helping Allied airmen evade capture from both Air Chief Marshall Lord Arthur Tedder of the Royal Air Force on behalf of the British people, and from General Dwight Eisenhower, expressing the gratitude of the American people.
Split into simpler sentences: She received a commendation for her participation in the resistance from Air Chief Marshall Lord Arthur Tedder of the Royal Air Force, was on behalf of the British people, thanking her for her role in aiding members of the Allied forces to evade capture. The second was signed by General Dwight Eisenhower, expressing the gratitude of the American people.