The Penang-based Monsoon Group gave Germany a continuing underwater presence in the Indian Ocean. The group made about forty deployment attempts, and some successful boats achieved substantial results. German, Italian, and Japanese submarine activity forced Axis anti-submarine forces to identify contacts cautiously. The danger of attacking an ally meant they could not treat every unidentified submarine as an enemy. That caution gave Allied boats an operational advantage.
Chapter · 58:38-59:42
The Monsoon Group complicated submarine identification
German boats at Penang gave the Axis an Indian Ocean submarine presence, but mixed German, Italian, and Japanese operations made friendly identification unusually restrictive.