What was the initial goal for Hedy Lamarr and George Antheil's frequency-hopping work?

To securely guide Allied torpedoes

The original application for the frequency-hopping spread-spectrum technology developed by Hedy Lamarr and George Antheil was highly strategic and military in nature. They designed the system with the explicit intent of controlling Allied torpedoes in a manner that would resist enemy attempts to jam or disrupt the guidance signals. This required the signal to rapidly change, or hop, between various carrier frequencies, making detection and interference exceptionally difficult. Although the technology was designed for warfare guidance, the core concept of resisting jamming became crucial for later civilian wireless applications operating in signal-dense environments.