Airpower

Primarily from U.S. navy-carrier based aircraft, Allied airpower crushed shipping nodes and closed sea lanes on their own. When computing the campaign as a whole, Allied airpower accounted for a combined 752 vessels and over 2.5 million tons of destroyed shipping. Aircraft delivered significant blows to Japanese shipping during large offensive operations, a trend which accelerated from the start of 1944 through to the end of the war. U.S. naval carrier-based aircraft massed their assaults on high volume ports and heavily trafficked shipping nodes. Such attacks neutralized major anchorages at Rabaul (13 Jan – 14 Feb 1944), Truk (Operation Hailstone, 17-18 Feb 1944), the Palau Islands (Operation Desecrate One, 30-31 Mar 1944), Guam (The Second Battle of Guam, 21 July – 10 August 1944) and the island of Morotai (15 September – 5 October 1944). Those operations sunk over 100 merchant vessels which totaled over 400,000 tons of shipping. Half of these vessels were lost on the coral lagoon of Truk as a result of Operation Hailstone. More importantly, these raids closed critical shipping lanes and freed up the submarine fleet to pursue other targets, thereby strategically undermining the Japanese empire.

The raid furthered another trend: the rapid reduction in the average tonnage destroyed by the Allies. Between 1944 and 1945, the Allies sunk 45% fewer tons of merchant shipping but only 28% fewer vessels. The key to this discrepancy is the drop in average tonnage between 1944 and 1945—4,105 and 2,566 tons, respectively. Capped off by the South China Sea raid, the cumulative war effort deprived the Japanese merchant fleet of its largest vessels and closed off its busiest SLOCs. With the Japanese empire split in two, Allied war planners focused on closing the small, coastal waterways and local shipping lanes which connected the Japanese Home Islands to each other, Korea, and northern China.