''He was experienced,'' recalled commander Eloy Gutiérrez Menoyo, 74, in a phone interview from an apartment outside Havana. ``He spoke little Spanish, but we took in anyone willing to take up arms against the dictatorship.''

While Morgan had a poor U.S. Army record, ''he was in a position to teach the young [rebels],'' said Encinosa. ``You're talking about some who never knew how to fire and clean a gun. That's what Morgan brought to them.''

In one of his first encounters with the enemy, Morgan showed his experience while revealing his lack of Spanish.

Gutiérrez Menoyo ordered his men to hold their fire as an army patrol approached. The goal: to capture the soldiers for their weapons.

''I asked everyone to confirm they understood my orders, and all, including William, nodded in agreement,'' Gutiérrez Menoyo recalled.

But when the soldiers broke through the brush, Morgan opened fire, wounding several. The soldiers escaped but returned with more men, chasing the rebels deep into the mountains for several days.

Gutiérrez Menoyo ended up scolding Morgan, but it was clear the American ''possessed tremendous ability,'' said Gutiérrez Menoyo, who spent 21 years in prison after falling out of favor with Castro.

During later skirmishes with troops in Fomento, Saltillo, Padrero and La Diana, Morgan inflicted numerous casualties.

He also earned respect among his men. After one battle, he carried a wounded rebel on his back ''all the way from the scene of the battle to the mountains, where he was treated,'' according to the 1979 book Merc: American Soldiers of Fortune.

Within a short time, Morgan's troops had fought more than 15 engagements -- losing none, according to Merc.

One rebel particularly impressed by Morgan was Olga Rodríguez, who fled to the mountains after she was accused of making bombs during the resistance movement in Santa Clara.

She watched as he was put in charge of five men, then a larger column, and finally promoted to comandante, the equivalent of major.

As he lost more men in fighting, Morgan became more committed to the revolutionary cause, Rodríguez said. ''I could see that he felt for my people,'' said Rodríguez, who married him in late 1958. She is now Olga Morgan Goodwin.

A turning point for the rebels was in November 1958 when they received a letter from Guevara saying the 26th of July Movement -- Castro's force -- was going to take over the Second Front.

Angered by the note, the Escambray rebels were determined to run their own unit, recalled Osiel González.

Now living in Miami, González said he was livid over the way the letter was signed, simply, ``Che.''

'It was as if we had sent a letter signed `Chico,' '' González said. ``It denoted a lack of respect.''

When more than 100 men from Castro's front arrived in November, Morgan and his rebels surrounded them and stripped them of their weapons, according to interviews and published accounts.

Soon afterward, Guevara showed up, angry. ''He was humiliated by the disarming of his men by the Morgan-trained guerrillas,'' wrote authors Brown and Mallin.

For a moment, the two rebel leaders -- Morgan and Guevara -- refused to back down. González said he later learned that Morgan challenged Guevara to draw. ''One of Morgan's most important roles was his part in defining our stand,'' González said.