The Oath That Never Expires

A Marine’s Journey from the 516 to the Battlefield of Cybersecurity

Veterans Day 2026 | Tom Brennan | USMC Veteran | Founder & CEO, Proactive Risk

There are things you leave behind when you leave the military.

The uniform. The barracks. The early mornings. The long days. The familiar sounds, routines, and responsibilities that become part of your life.

But there is one thing you never leave behind.

The oath.

I was a young kid growing up in Long Island, New York, in the 516 area code. I was fascinated by technology, computers, and figuring out how things worked. I was a hacker before cybersecurity was even a mainstream word. I liked taking things apart, understanding systems, and finding ways to make them do things others hadn’t imagined.

I couldn’t have known then that this curiosity would eventually become my profession.

But before the business cards, boardrooms, technology companies, and cybersecurity conversations, there was another calling.

The United States Marine Corps.

And it would change the way I approached just about everything for the rest of my life.

Earning the Title

My Marine Corps journey began as an 0311 Rifleman.

If you’ve served in the infantry, you understand that it is about more than learning a MOS. It is about learning responsibility, discipline, humility, and what it means to be part of something bigger than yourself.

You learn to depend on the Marine standing next to you.

You learn that leadership isn’t about rank on your collar or who gets the credit. It is about stepping up, doing your job, and making sure the people around you can do theirs.

I eventually volunteered to become an 1833 Amphibious Assault Vehicle Crewman, serving with the 2nd Marine Division, 2nd Assault Amphibian Battalion.

It was another commitment, another challenge, and another opportunity to serve.

During the Gulf War I era, I served on active duty, full-time, stateside. Our nation was engaged in a major military conflict, and readiness, preparation, and the responsibilities of military service were very real.

Not every Marine’s story involves being deployed into combat. Mine is not a combat story, and I would never pretend otherwise.

But service is not a competition over whose experience was hardest or whose story sounds the most impressive.

We each had a job to do. We took the oath. We accepted the responsibility.

And we served.

To my fellow Marines from the 2nd Marine Division and 2nd Assault Amphibian Battalion: I haven’t forgotten you, the experiences, or the lessons.

Semper Fidelis.

The Marine Never Really Leaves

Years have passed. Life has changed. My responsibilities have changed.

I’m now a husband, father, entrepreneur, and CEO.

But I still recognize the Marine Corps in the way I approach business, leadership, and life.

Preparation matters.

Accountability matters.

Trust matters.

And when people depend on you, you don’t get to simply walk away when things become difficult.

Those lessons have followed me into every chapter of my civilian life.

The young hacker from Long Island eventually found himself in an entirely different kind of battlefield.

Cybersecurity.

A Different Mission. The Same Commitment.

Today, I am the Founder and CEO of Proactive Risk, an intelligence-led cybersecurity and risk management company.

Our mission is to help protect businesses, organizations, and the people behind them from adversaries who are constantly looking for weaknesses.

We assess vulnerabilities, anticipate threats, build defenses, and help organizations prepare for incidents before they become disasters.

The technology has changed dramatically since my early days of exploring computers.

The adversaries have become more sophisticated.

The stakes have become enormous.

But the philosophy remains familiar.

Know your environment. Understand the threat. Prepare your people. Protect what matters.

In the Marine Corps, readiness was not optional.

In cybersecurity, neither is preparation.

At Proactive Risk, our philosophy is:

ADVERSARIES PLAN. WE PREEMPT.

I sometimes think about the connection between that young kid in the 516, the 0311 Rifleman, the 1833 AAV crewman, and the person sitting in the CEO’s chair today.

Different chapters. Different responsibilities.

One common thread: protecting others.

The uniform changed. The mission evolved. The oath never expired.

To My Brothers and Sisters Who Took the Oath

This is the part of Veterans Day that means the most to me.

To the Marines, soldiers, sailors, airmen, Coast Guardsmen, and Guardians who have served this country: I salute you.

To those who served in combat, I recognize the sacrifices and burdens that come with experiences most people will never fully understand.

To those who served stateside, maintained readiness, supported operations, and stood prepared when called upon, your service matters.

To those who served during peacetime, wartime, and every uncertain moment in between, thank you.

To those who are still wearing the uniform, standing watch, and carrying the responsibility today, know that we have not forgotten you.

And to the veterans who have transitioned into civilian life and are now building companies, raising families, teaching, protecting communities, mentoring young people, and helping other veterans find their way:

Keep going.

You don’t need a uniform to continue serving.

You don’t need a military title to lead.

And you certainly don’t need recognition to make a difference.

One of the things I respect most about our veteran community is that many of its best people are not looking for applause. They simply continue showing up.

They look out for one another.

They keep their word.

They take responsibility.

They understand that the mission is bigger than the individual.

That is a brotherhood and sisterhood worth protecting.

What I Hope the Next Generation Understands

I hope young Americans understand that military service is about more than a job, a paycheck, or a line on a résumé.

It is an opportunity to challenge yourself.

To develop discipline.

To discover what you are capable of.

To build lifelong friendships.

To learn leadership through responsibility rather than entitlement.

And to become part of a tradition much bigger than any one of us.

You don’t have to become a Marine to make a difference. But you should understand the value of service, sacrifice, commitment, and putting something greater than yourself first.

Those principles are worth carrying into every profession and every generation.

The Oath Never Expires

As I reflect on my journey this Veterans Day, I find myself thinking less about what I accomplished and more about the people, experiences, and lessons that shaped me.

The young hacker growing up in Long Island’s 516 area code.

The decision to become a Marine.

The 0311 Rifleman.

The decision to volunteer for 1833.

The Marines of the 2nd Marine Division and 2nd Assault Amphibian Battalion.

The years of building a career and eventually a company.

And the people I have the privilege of protecting and leading today.

I am proud of every chapter.

But most of all, I am proud to belong to a community of Americans who raised their right hand and made a promise to this country.

We may disagree about politics. We may come from different backgrounds. We may have served in different branches, different decades, and under very different circumstances.

But we share something that cannot be manufactured or purchased.

We took an oath.

And that oath was never meant to expire when our military service ended.

It was a commitment to something greater than ourselves.

Once you take that oath, you carry a responsibility for the rest of your life.

So to my fellow veterans, my brothers and sisters in arms, and everyone who continues to serve this great country:

Thank you. I am proud to stand among you.

Semper Fidelis.

God bless our veterans. God bless those currently serving. And God bless the United States of America.

— Tom Brennan
USMC Veteran
MOS 0311 | MOS 1833
2nd Marine Division | 2nd Assault Amphibian Battalion
Founder & CEO, Proactive Risk
https://www.proactiverisk.com

PROACTIVE RISK — Intelligence-Led Cybersecurity & Risk Management

Predictive. Protective. Defensible.