My son Charlie, a junior at Ohio State, is a grunt corporal in the Marine Corps Reserve. When he graduates, he hopes to take a commission as an officer. In the meantime he’s on call, ready for deployment at a moment’s notice. Since the terrible events of Sept. 11, that fact has taken on new meaning for my husband and me. Just 24 hours after the terrorist attacks, a Marine sergeant called our house to confirm Charlie’s number at school. “In case we need to reach him quickly,” he explained.

The worry that Charlie might be called into action isn’t a new one. We knew he could be sent overseas to Kosovo when our government considered sending in “ground pounders,” and more recently to Macedonia, a situation deemed perfect for a reserve unit, since it was a 30-day commitment. This time, however, our armed forces face more than a temporary peacekeeping mission. They must defend our country as part of a military response that could last years.

I remember the day Charlie told us he had enlisted. My husband, Jack, a Vietnam vet, responded with outward calm. “Well, I guess if you signed up, you’re in,” he said, looking over Charlie’s copy of his enlistment contract. “This is what you want?” “Yup,” Charlie answered. I looked at both of them as if they were strangers. Charlie had spoken about his interest in becoming a military officer before, but I had always assumed he would finish college before seeking a commission. It had never crossed my mind he might join without talking to us. Now he was facing an eight-year commitment–four as an enlisted reservist, four as a commissioned officer.

After Charlie left the room, Jack sat at the kitchen table, his reserve gone. He looked as if he’d been hit with a baseball bat. “What do you really think?” I demanded. “I suppose he could do worse than serve his country for a few years,” he said.

Our friends were less sanguine. Several suggested getting a lawyer and getting him out of the enlistment contract. He was still a senior in high school, they reasoned; he had no idea what he was getting himself into. For us, though, second-guessing his judgment was not an option. Enlistment was not the path we might have chosen for him, but we wanted to support his decision. The last thing he needed from his parents was doubt and fear. If he could take up the challenge of military life, we could do our part to encourage his resolve.

Now the reality of Charlie’s being pressed into action looms ever closer. Though Charlie tells me he’s prepared to fight (“Mom, this is what I’m trained for”), I’m struggling to hold on to my own shaky resolve. Sometimes I’m rational, recognizing the good we’ve enjoyed as citizens and how there are many other members of the military and their families who will be asked to give as well. Sometimes I’m fearful, forcing myself not to imagine all the possible outcomes if he is called up. Sometimes I’m angry, regretting every stupid war movie we ever let him watch.

It’s the story of my grandmother Mary that sustains me. She sent three sons off to fight in World War II. The two older boys, John and Mike, went to Europe, gleaning nine battle stars between them. She reluctantly signed for my Uncle George, a 17-year-old who went with the Marines to the South Pacific and Kwajalein. They all came home, thank God. If she, like so many other mothers, could face the possibility of their loss, I can let my son go.

As I’ve learned of the bravery of the New York firefighters and police in the last few weeks, I’ve found a new determination to face whatever lies ahead. It will be my turn to be generous if and when my son is called to serve. Maybe the flag-waving will have stopped by then and selflessness will be out of fashion. If so, I’ll draw courage from the example offered by my grandmother and the heroes of Sept. 11.

Last week, at the recommendation of the Marine Corps, I helped the young man I gave birth to 22 years ago prepare his will. While I still have fears about what might happen, I’m ready now to take up the challenge in the last couplet of the cadence call: “Mothers of America, don’t you cry./Marine Corps way is to do or die.”