What system was designed to replace the Trojan Spirit II?

The system designed to replace Trojan Spirit II is Trojan Spirit III. This evolution represents advancements in technology and capabilities, aiming to enhance the performance and reliability of data communications and intelligence gathering in military operations. Trojan Spirit III incorporates modern features to ensure more efficient processing of intelligence and interoperability with contemporary systems, reflecting the ongoing need for military adaptability in the face of emerging threats.

Understanding the context of the other choices is also valuable. While MCN-AE is related to military communications, it does not directly replace Trojan Spirit II. Shadow Data Network and Secure Data Relay are distinct systems with other specific functions that do not pertain to the direct evolution of the Trojan Spirit series. Therefore, recognizing that Trojan Spirit III directly succeeds Trojan Spirit II is key to understanding the continuity in military intelligence systems.