The primary weapon of the Swordfish was the aerial torpedo, but the low speed of the biplane and the need for a long straight approach made it difficult to deliver against well-defended targets. Swordfish torpedo doctrine called for an approach at followed by a dive to torpedo release altitude of . Maximum range of the early Mark XII torpedo was at and at . The torpedo travelled forward from release to water impact, and required another to stabilise at preset depth and arm itself. Ideal release distance was from target if the Swordfish survived to that distance.