The attached R-class battleship changes the escort calculation after Emerald's limitations are considered. Its 15-inch guns posed a threat that a Deutschland-class raider could not safely accept. The German ship was slow enough for the battleship to have a realistic chance of bringing those weapons to bear. Emerald remained useful within the formation, but the capital ship supplied the decisive deterrent power.
Notable Point · 23:29-23:52
Why battleship cover mattered against a Deutschland
An attached R-class battleship supplied the decisive deterrent against a Deutschland-class raider because its 15-inch guns could overwhelm the smaller German ship.