Complex sentence: As the "Civilian" was coaling the cruisers, the German vessels approached and the British warships cast off immediately to engage in battle, during which Admiral Von Spee's battleships "Scharnhost" and "Gneisenau", plus escorting cruisers, were sunk.
Split into simpler sentences: As the "Civilian" was coaling the cruisers, the German vessels approached and the British warships cast off immediately to engage them. In the ensuing battle Admiral Von Spee's battleships "Scharnhost" and "Gneisenau", plus escorting cruisers, were sunk.