Why is Tim Walz's military record the target of Republican attacks?

The transcript discusses the controversy over Tim Walz's military record, focusing on criticisms from JD Vance and a defense by Pete Buttigieg. Vance accuses Walz of lying about his service for political gain, while Buttigieg argues that the criticism is unfounded and highlights Walz's honorable service. The discussion emphasizes the importance of accuracy in representing military service and the implications of political attacks on veterans.

What does the phrase 'exception that proves the rule' imply in the context of Tim Walz's military record?

How long did Tim Walz serve in the military, and how does this compare to the typical retirement period?