When a commander's original service matters less than systems management

At what command level does an officer's original service matter less?

At theater or supreme-command level, where coordinating allies, resources, logistics, and specialist subordinates outweighs direct tactical expertise in one service.

The answer places the change at the level where a commander must handle political relationships and secure resources for subordinate forces. Providing those subordinates with authority and support becomes a major part of the job. Eisenhower and Kesselring are used as examples of commanders working between military strategy and political demands. A follow-up adds the need to resolve disputes and keep commanders from different services cooperating. On this account, an officer's original service matters less as these coordinating responsibilities grow.