POOR JIM MACKEY.

He's a retired Coast Guard officer and current naval-science instructor at Ben Franklin High School, where he works in the Junior ROTC program.

When he was recruited for the job 18 months ago, he wasn't sure he wanted to commute from his home in Brigantine, N.J., all the way to Ben Franklin, at Broad and Spring Garden streets.

Until he met the man who'd be his mentor: Retired Marine Master Gunnery Sgt. Andrew Worley, nicknamed Master Gunns by the 114 cadets and staff.

Mackey saw how the short, smiling, cherubic Worley connected with students, helping often-unfocused boys and girls mature into confident, determined young men and women.

After high school, many entered the military or college - including those who, before JROTC, never thought they were college material. And they stayed in touch with Worley, inviting him to their graduations, weddings and kids' christenings, their photos crowding Worley's desk.

"He loves the kids; they love him," says Mackey, 51. "I knew he was the guy to learn from."

The reason I feel bad for Mackey is that Worley, 60, who founded Franklin's JROTC program in 2003, has resigned. Today, he'll collect the last of his things and take another round of hugs from students who say he's the best teacher, role model and/or father they've known.

Which means that there will be a Worley-size hole at Ben Franklin that everyone will look to Mackey to fill. Not that Mackey has any illusions that it's possible.

"There will never be another Master Gunns," he says.

One of six sons born to a Bridesburg military father and homemaker mother, Worley was a bright, underachieving troublemaker at Mastbaum High School.

Drafted after graduation, he says Vietnam grew him up in a hurry. Twice wounded, he couldn't speak for years about the injuries that earned him two Purple Hearts. He stayed in the military, earned commendations for multiple military operations, and figured he'd enjoy his hard-earned retirement with his wife, Terry, in Lebanon, Pa., about 80 miles northwest of Philly.

But he was bored.

"I need to be needed," he says.

So he leaped when he was asked to create a JROTC program at Ben Franklin. Even though it was a two-hour commute each way from home. Even though he'd be working with kids for whom authority is often a problem. Even though his own upbringing by two parents in a stable, all-white neighborhood was so different from the hard adolescence his students would be experiencing.

"My work was cut out for me," he says. "These kids didn't need me to be their leader but to bring out leadership in them. They needed me to love and respect them and show them how to treat other people that way, too."

The curriculum was the usual academic subjects, plus military drills and instruction common to JROTC programs everywhere.

What was not usual was Worley's depth of caring.

He invited kids to call him with any problem, day or night.

He and his wife hosted barbecues for the students, many of whom had never been outside the city, let alone seen rolling hills like the ones where Worley lived.

He snagged tickets to the annual Army-Navy football game and used his own money to take his cadets to the games, whether in Philly or Washington.

He paid for SEPTA passes and lunches and counseled students through problems bigger than any he'd faced: the murders of friends; incarceration of parents; grinding poverty that broke his heart.

When one student disappeared, Worley used his connections to find her in Harrisburg. Then he and his daughter retrieved her and drove her home to her worried mother in Philly - an odyssey that took hours.

"What a long night!" he says.

He'd burn out, he says, if his cadets didn't respond in a way that reminds him that tough love, discipline and support are the miracle cure to what ails all but the most broken children. And even those he refuses to write off.

Like Andre Edwards, who had just returned to Ben Franklin after incarceration and was practically terrorizing the school. He was on the verge of expulsion when principal Christopher Johnson referred him to Worley.

"I was a mess," says Andre. "But whatever I tried with Master Gunns, he refused to get angry. He listened. He cared about me like a father. I calmed down."

So much so that Worley and his wife now consider Andre a son. And - wonder of wonders - Andre, now 21, works at Ben Franklin as a nonteaching aide, working with troubled kids.

It awes principal Johnson.

"There are no words to describe Master Gunns," he says, trying not to let his voice crack. "There is nothing he won't do for the kids and the school. When I heard he might be leaving, I actually avoided him for two weeks because I wanted to stay in denial."

Making the decision to leave Ben Franklin, says Worley, has been one of the hardest decisions of his life. He learned that the JROTC program at Owen J. Roberts High School in Pottstown was going to discontinue, because its instructor was retiring.

"Much as I wanted to stay," he says, "I couldn't let that program fall apart. My cadets here are in good hands with Jim [Mackey]. And I have big plans for joint programs with both schools."

When he told his JROTC commander that he'd miss terribly his Ben Franklin cadets and colleagues because they were like family, "He told me, 'Ben Franklin is your old family. This will be your new family.'

"I told him, 'They're all my family. It just got bigger.' "

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