Pete Buttigieg is one of 10 presidential candidates taking part in a Democratic debate Tuesday, July 30, at 8:00 p.m. ET on CNN. Ten others will debate on Wednesday evening. He is the mayor of South Bend, Indiana. The views expressed are his own. View more opinion articles on CNN.

(CNN) While I was overseas in Afghanistan, the greatest lesson I learned wasn't about counterterrorism or geopolitics or scouting out the best food in the chow hall. It was learning to trust my life to people completely different from me. The military I belonged to drew people from all ages, racial backgrounds and regions of our country. In many ways, we had nothing in common except the fact that we were all American.

Pete Buttigieg

On each one of the 119 trips I took outside the wire -- be it driving or guarding a vehicle -- I learned what it meant to trust someone else with my life, and vice versa. The men and women who got in my vehicle didn't care whether I was a Democrat or a Republican, or whether my father did or didn't have papers when he immigrated here. They cared about whether my M4 was locked and loaded, and whether I had selected the route with the fewest improvised explosive device threats. They just wanted to get home safe, like I did.

It was a life-changing sense of trust in others -- and one I wish more Americans had. But I don't believe you should have to go to war in order to build that kind of trust and understanding, which is why I'm determined to knit together our social fabric through a new call to service.

At this moment, when faith in our institutions is at record lows -- when social media and deepening polarization have put us into bubbles and less than 6 in 10 Americans express trust in their fellow Americans -- we can't heal our democracy unless we first heal the deep divisions between us. National service would help achieve exactly that.

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