One monitor flooded its port wing tanks to gain extra elevation for bombardment. Mersey and Severn then advanced with air support and supporting fire against prepared German positions. They sought a range near 10,000 yards, where their 6-inch guns could reach Königsberg but the cruiser's weapons could not answer. A navigation error on the first attack brought HMS Mersey too close and exposed her to damaging return fire. On the second attack, the monitors found the intended range and disabled Königsberg, whose commander then ordered her sunk with one of her own torpedoes.
Chapter · 40:27-42:55
Mersey and Severn force the Rufiji Delta
The Humber-class monitors crossed the delta's shallow approaches, corrected an initial range error, and disabled Königsberg with 6-inch gunfire.