U-98 under Wilhelm Schulze returned to the region for a unique mine-laying operation on the 5th of August, entering between Bermuda and Savannah on a course southwest for the Jacksonville, Florida area. Crucially, U-98 laid twelve mines off Jacksonville, Florida on the 9th of August. The delicate mine-laying operation might explain the dearth of other targets the submarine attacked, as the safety of the mines from depth charging would have been paramount in the captain’s mind.
On the 10th of August – just one day after the mine field was laid – it claimed its first and only victim: the US armed merchant cruiser Bold (AMC 97) which struck a mine off Jacksonville and necessitated a shutdown of the river until the mines could be cleared some time later. The USS Bold was 185 tons and was repaired and returned to service. U-98 continued back from whence it came, crossing into the waters off South Carolina on the 11th of August and out of the area after a patrol in the region of just six days.
Unlike some mine fields which never sank any ships, that laid by Schulze was effective inasmuch as the enemy learned of it immediately and was forced to take costly counter-measures. Mines were effectively a tool of terror and confusion rather than of a strict tonnage war. When the Allies used them – off Hatteras and off Key West as we shall see – mines often claimed more “friendly victims” than the enemy (the US destroyer Sturtevantsunk in an Allied minefield off Key West being a prime example).
At least half a dozen ships were lost to Allied mines off the eastern and US Gulf seaboards and no Axis submarines were sunk or damaged by them there. It would not be the only mining operation of any port in the Bahamas “rectangle”, as San Juan Puerto Rico was mined by U-218 in 1944, to no effect.
U-98 began its patrol in St. Nazaire on the 14th of July. On her return from her second patrol to Florida the boat was refueled by U-462 late in August west of the Azores. She returned to France on the 16th of September, 1942 (Wynn, Vol. 1, p.79).
SOURCES: Gudmundur Helgason, Rainer Kolbicz, www.uboat.net, 2011m Kenneth Wynn, U-boat Operations of the Second World War, Volume 1 and Volume 2, 1997