Editor's Note: This is the second in a five-part series.

On one morning in November 1943, in the jungles of the Pacific island of Bougainville, Marine PFC Rufus Mayo was in a panic, scanning the scene around him. Desperate for help, he yelled to another marine—where was Caesar?

At dawn the Japanese had mounted an attack on the marines. The dog handlers had brought their dogs into their foxholes, resting easier knowing their dogs were there to keep watch. Caesar, a large German shepherd, had heard the attackers coming before the men had heard them, and in his instinctive reaction to protect his handler, Mayo, sleeping beside him, the dog had launched out of the foxhole.

When Mayo realized what was happening he shouted at Caesar to stop and come back. But when the dog turned to obey, a Japanese soldier opened fire, sending three bullets into his body. A battle ignited, and in the chaos Caesar went missing.

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Afterward, Mayo and another marine searched for the dog. They found a trail of blood, leading them back to the battalion's command. The dog had managed to return to his other handler, PFC John Kleeman, and collapsed behind a bush.

Mayo rushed to him, cradling him gently. The marines around them moved quickly, breaking down two poles and attaching a blanket to build a makeshift litter to carry the dog to the hospital tent.

While the doctors worked to remove the bullets, his handlers paced outside. Two bullets could be removed, but the surgeon felt it was too risky to take out the third, which had lodged near the dog's heart. In the end, the dog would prove stronger than that bullet, and after only three weeks of rest and recovery, he was back on active duty.

View Images Marines carry a wounded German shepherd believed to be Caesar to the hospital tent on Bougainville. PHOTOGRAPH BY US MARINE CORPS OFFICIAL

Caesar would prove the value of a dog's role in war several times over the course of his service in World War II. During one deployment, heavy rains rendered the marines' walkie-talkies unusable, and Caesar ran messages back and forth repeatedly between his handlers while evading sniper fire.

On another occasion, Caesar saved Mayo from a grenade attack. In a letter home, the handler wrote to his family, "I would not give Caesar up for a general's commission."

Like the other 10,000 dogs that would serve in the United States military during World War II, Caesar was donated in a show of patriotism and civilian solidarity by his owners, the family of Max Glazer, who lived in New York City, as part of the Dogs for Defense program.

He was legendary in his Bronx neighborhood for delivering groceries, carrying packages in his mouth back to the Glazers' fourth-floor walk-up. And once he was told to "take it to Mom," Caesar couldn't be diverted from his task.

View Images A group of marines pose with their dogs, which were trained to find Japanese snipers, carry messages, and protect against ambushes. PHOTOGRAPH BY BETTMANN/CORBIS

When the draft came, the Glazers' three sons left home one by one. And, after the family saw the military's call for dogs, it seemed to make sense that the canine member of their family should enlist as well. Caesar—obedient, loyal, and vigilant of strangers—had all the makings of exemplary soldier. And like many other families, it was not easy for them to watch their sons—or their dogs—leave for war. When the Glazers sent Caesar off, there wasn't a dry eye in the family.

Caesar was one of the dogs who made up the very first Marine Dog Platoon attached to the Second Marine Raider Regiment and deployed to Bougainville in the fall of 1943. The war dog platoon consisted of 55 men and 24 dogs, three of which were German shepherds, the rest Doberman Pinschers—these dogs would forever after be known as Devil Dogs. Of the platoon members who deployed and served on Bougainville until January 23, 1944, only four did not return—two dogs and two handlers.

In a report to his superiors, the commanding officer of the Marine Raider Regiment wrote that the war dog platoon had been an "unqualified success." First on the list of the successes he recounted was: "Not one marine was killed while in a marine patrol led by a dog." Among others were how the dogs made it impossible for the enemy to make surprise attacks at night or infiltrate their camps undetected; how the scout dogs had "alerted to enemy ambushes and snipers"; and how they were so trusted by the Marine Raiders that these men "vied nightly to dig foxholes for the handlers in order to get the handlers and their dogs to bunk down with them."

Before they had stormed the beaches on November 1, 1943, Lt. Col. Alan Shapley, the commanding officer of the Marine Raiders, reportedly turned to his men and said, "I want you men to remember that the dogs are least expendable of all.

Coming tomorrow: Judy, Prisoner of War