The pilot lined up for another run, tracking a marker buoy they had released ahead of the initial attack. Eyeing the remnants of the sub’s fading wake, he gauged the vessel’s unseen path, then gunned the pig-bellied Catalina just past the buoy.

“Coming up on her,” he told the bombardier. “Release if you’ve got a target.”

The bombardier for the eight-man crew sighted the sub and flipped a toggle switch, releasing a second pair of depth charges stowed under the Catalina’s wings.

“Depth charges away. Spot-on this time, I’d say, Flight Lieutenant.”

“Let’s try one more for good measure, then see if we can raise a surface ship in the vicinity,” the pilot replied, already banking the plane hard over.

INSIDE THE BARBARIGO, the twin blasts shook the bulkheads with a deep shudder. The overhead lights flickered and the hull groaned, but no rush of water penetrated the interior. For a moment, the explosion’s deafening roar seemed to be the worst consequence, ringing in each crewman’s ears like the bells of St. Peter’s Basilica. But then the ringing was overpowered by a metallic clang that reverberated from the stern, followed by a high-pitched squeal.

The captain felt a slight change in the vessel’s trim. “Fore and aft damage reports,” he yelled. “What’s our depth?”

“Twelve meters, sir,” the pilot said.

No one in the control room spoke. A cacophony of hisses and creaks permeated the compartment as the sub dove deeper. But it was the sound they didn’t hear that prickled their ears—the splash and click of a pair of depth charges detonating alongside the submerged vessel.

The Catalina had dropped wide on its last pass, its pilot guessing north while the Barbarigo veered south. The last muffled explosions barely buffeted the submarine as it plunged beneath the reach of the depth charges. A collective sigh was expelled as, to a man, the crew realized they were safe for the time being. Their only fear now would be if an Allied surface ship could be summoned to renew the attack.

Their relief was cut short by a cry from the steersman.

“Captain, we seem to be losing speed.”

De Julio stepped close and examined a bank of gauges near the pilot’s seat.

“The electrical motors are operational and engaged,” the young sailor said, wrinkling his brow. “But I show no revolutions on the driveshaft.”

“Have Sala report to me at once.”

“Yes, sir.” A sailor near the periscope turned to retrieve the Barbarigo’s chief engineer. He’d taken only two steps when the engineer appeared in the aft passageway.

Chief Engineer Eduardo Sala moved like a bulldozer, his squat frame churning forward in a blunt gait. He approached the captain and stared at him with harsh black eyes.

“Sala, there you are,” the captain said. “What is our operational status?”