Which group first conducted a helicopter combat rescue?

The 1st Air Commando Group was the first unit to conduct helicopter combat rescue operations. This group played a significant role during the Vietnam War, demonstrating the effectiveness of rotary-wing aircraft in combat situations, particularly in rescuing downed aircrew. Their pioneering missions illustrated the importance of speed and flexibility in rescue operations, laying the groundwork for future air rescue protocols.

In contrast, the other options represent different units or aspects of Air Force history. The 99th Fighter Squadron is renowned for its contributions in WWII and its legacy in aviation but is not specifically linked to helicopter-based rescue missions. Fifth Air Force has a broader operational focus, integrating various airpower capabilities, while the Thunderbirds are primarily known as the Air Force's air demonstration squadron and not involved in combat rescue operations. These distinctions underscore why the 1st Air Commando Group remains the key figure in the development of helicopter rescue operations.