As a former Army Ranger Captain I know something about promises. I swore an oath to defend this great country. And while I was fulfilling that oath I served alongside some of the country’s bravest soldiers in Iraq and Afghanistan. These soldiers had all raised their hands and taken the same oath to defend our country and to sacrifice for all Americans. These men and women are some of our best, brightest, and most patriotic citizens. And some of them were gay. When I served in the military between 2002 and 2006, men and women with whom I served could be discharged because of their sexual orientation. They were told, by the thousands, that they were not good enough to sacrifice for this country because of who they loved.

Last week, the first academic study of the impact of the repeal of “Don’t Ask, Don’t Tell” was released by U.C.L.A.’s Palm Center. Co-authored by professors from the U.S. Service Academies and Marine Corps War College, the study concluded that the repeal had no overall negative impact on military readiness, recruitment, retention, or cohesion. But I didn’t need a study to tell me that.

The men and women with whom I served came from all backgrounds and corners of the country, but when we stepped foot on foreign soil our differences disappeared. What mattered most was whether the person to your left and right knew their job, whether you could trust them your life, and whether they would stand up against the stress and rigors of war. Simply put, what we had in common as soldiers was far more powerful than our differences.

When President Obama became the Commander-in-Chief he understood a fundamental truth about the military. He understood that the military is the standard bearer for American values, and today our military more accurately represents the values we ask our troops to defend. That makes our nation stronger. President Obama understood that when a patriotic man or women was willing to risk his or her life for our country it was wrong to say that they were not good enough because of who they loved. The President took a stand on the right side of history when he kept his promise and joined millions of Americans to repeal “Don’t Ask, Don’t Tell.”

Today we celebrate the brave service of gay and lesbian members of our military because, thanks to President Obama, we have taken another step forward towards a fairer and more just nation.

But the President didn’t stop there. President Obama knows that we have a sacred trust with those who serve our nation. It’s a commitment that begins at enlistment, and it must never end—we owe our veterans and their families the care they were promised and the benefits they have earned. That’s why President Obama is committed to ensuring that veterans can find work when they return home, receive the health care and benefits they’ve earned and have the chance to get a college education through the post-9/11 G.I. Bill. As millions of our servicemen and women return home from war, now more than ever we must fulfill our duty to them.

I now live with my wife and son in Colorado, but many soldiers never returned home, while others came home bearing the visible and invisible scars of battle. Time and again, President Obama has proven that when our servicemen and women and their families need help, he is there for them.

Our service members, veterans, and their families deserve four more years of a Commander-in-Chief who has their back. And that’s why I will continue to stand with my President, my Commander-in-Chief, Barack Obama.