Latta was a veteran of nine war patrols and holder of the Navy Cross, earned while commanding officer of the submarine USS Narwhal (SS-167).

Sadly, during that period, on 3 December, Chief Machinist's Mate Pat Cole died of coronary thrombosis while Lagarto lay at Saboya Anchorage, off Perlas Island, Panama.

Releasing their escort four and a half hours out, the two boats proceeded in company, conducting dives and drills daily and acting as targets for each other on alternate days.

Tragedy struck the next day, however, when an automobile accident on Saipan resulted in serious injuries to two of Lagarto's more experienced officers: Lieutenant Walter R. Shaw, a "mustang" (commissioned from the enlisted ranks) veteran of three war patrols, and Ensign Allen G. Brewington, who, like Shaw, was a mustang but a veteran of nine patrols, including one in Haddock for which he had earned the Silver Star.

At noon the same day (8 February), while Lagarto mourned her loss, Commander Latta informed the "wolfpack" that its being behind schedule would not permit coordinated practice firing.

A quarter of an hour into the first dog watch on 12 February, Lagarto sighted four B-29s; contacting two over her VHF (very high frequency) radio equipment, she "received [the] dope on [the] picket vessels" they sought.

"With excellent SCR (Set, Complete, Radio) communication," Commander Latta "outlined [the] plan to [the] other skippers as easily as if we were in the same wardroom".

With Sennet on the left flank and Haddock on the right, and Lagarto as guide in the center, the boats some 3,000 yards (2,700 m) apart, Latta planned to close to 7,000 yards (6,400 m), then turn right about 50 degrees, to put the seas and wind in a most favorable position and still close the range, allocating Sennet the picket to the north, Haddock the one to the south; Lagarto, meanwhile, would direct the fire to whichever vessel "appeared to be offering the most opposition."

At 06:20 on 13 February 1945, Lagarto manned her battle surface stations, and opened fire with her number one 5-inch (13 cm) gun 12 minutes later on the clearly unsuspecting enemy that lay "nicely outlined against [the] red eastern sky" 7,200 yards (6,600 m) distant.

Latta reported subsequently, as one of the guard boats managed to transmit a dispatch as chaos descended suddenly upon her: "Gun attack by submarines in position 30-00N, 136-30E...” Lagarto's photographer seemed elated (in a "happy daze," the commanding officer reported) at the apparently photogenic aspect of the action he was recording, repeating "Oh boy, Oh boy!"

No such elation seized the enemy, however, who determinedly fought back against his heavier adversaries, as the action progressed, with whatever caliber weapon lay at hand.

Haddock, having expended the last of her 5-inch (13 cm) ammunition, headed for the latter, lying riddled and burning, to finish her off, but No.3 Showa Maru sank before the submariners could man her 40-millimeter guns.

Sennet neared No.8 Kotoshiro Maru's side "to see if anything worth salvaging was left", but apparently found it "too hot" and pulled clear.

"Latta's Lancers" having summarily disposed of the two guard boats (there were no survivors from either Japanese vessel) with no loss to themselves, Lagarto, Haddock, and Sennet formed a scouting line and continued their search.

During the first dog watch on 13 February 1945, a lookout in Haddock, despite poor visibility conditions, spotted two more guard boats lying-to about 10,000 yards (9,100 m) distant.

Since Haddock had expended the last of her 5-inch (13 cm) ammunition in the engagement with the two pickets that morning, Latta ordered her to maintain contact while Lagarto and Sennet opened to the westward as before.

"No likelihood of bright eastern sky today", her commanding officer later recounted, "all heavy gray overcast and seas less favorable to gun firing."

Going to "battle surface" 15 minutes later, Lagarto opened fire on the right-hand vessel at 5,600 yards (5,100 m), swinging to the right to bring both of her 5-inch (13 cm) mounts to bear, "cold seas washing over [the] gun crews."

Sennet reported numerous holes in her superstructure and one man wounded from the "extremely accurate" fire, but Lagarto emerged from the encounter unscathed.

Later that day, she heard "distant, heavy depth charge explosions", prompting Latta to write: "Hope Haddock is not paying for our attack..." Lagarto submerged to conduct a patrol of Van Diemen Strait the following day, 25 February 1945, and the heavy seas encountered rendered control difficult; she encountered 8–10-degree rolls at depths of 8 feet (2.4 m) between periscope observations.

She conducted a submerged patrol off Bungo Suido the next day, sighting a veritable parade of guard boats similar to those encountered and destroyed less than a fortnight before.

Ultimately departing her patrol area on 13 March 1945, bound for Subic Bay and a refit, Lagarto shaped course for a rendezvous with Haddock the following morning.

Decreasing the range, both American boats gained on the enemy, but "Haddock found a few more turns and began to pull ahead rapidly."

Brockman and mutual well-wishing", Latta wrote subsequently, "[Lagarto] took departure and set course for previously assigned route to Subic Bay."

Lagarto joined her escort, Douglas A. Munro an hour into the morning watch on 20 March 1945, and after anchoring for a sound test in Subic Bay, moored alongside the submarine tender Howard W. Gilmore to commence a refit.

Beneath a clear, dark, sky, Baya began her attack at 12 knots (22 km/h) through the flat sea, from off the convoy's starboard bow, setting her torpedoes to run at four feet.