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In March, I went to Chicken Street in Kabul, a well-known shopping stop for those Americans and foreigners who are allowed to venture outside the Green Zone. In one of my favorite shops, I noticed a tray of silver in one of the display cases. As the shopkeeper splayed the trinkets out on the glass, he uncovered a single gold disc, slightly larger than the others. I couldn’t help but laugh when I read the inscription: “Chief Petty Officer’s Mess.” Here in the heart of Kabul, I’d found a challenge coin from a group of American senior enlisted sailors who decided their deployment here warranted permanent commemoration. Between 2010 and 2011, these nameless chiefs — “tried, tempered & trued,” according to the coin’s engraving — had brought their maritime traditions from the sea to landlocked Afghanistan. I too had spent that time in the country, though there was no coin honoring my unit or the mud-brick compound we called home.

Challenge coins are beloved by those who commission them — usually American military officers or staff noncommissioned officers. The name comes from their original purpose in Special Forces units, where they seem to have originated: If challenged to prove what unit they were in, soldiers could pull out their coins as proof. Once exclusively an Army phenomenon, the practice expanded to the other services during the global war on terror. The coins are typically handed out to members of a unit after a deployment, or given as ceremonial gifts to partnered units and allies, tchotchkes from a deployment spent in combat (or at least in the same country as combat). Unlike official Defense Department-issued medals, they are a rare chance for self-expression for career military people who want to memorialize themselves and their actions, a tangible way of thanking yourself for your own service by showering those around you with tokens noting your rank and leadership. Yet despite this unique opportunity to wax artistic, most challenge coins look incredibly similar: copper or gold-plated, a flag or unit crest on one side and an eagle or some other symbol of military strength on the other. This uniformity is not by Defense Department order or field-manual regulation, but by unconscious consensus. Even these self-important attempts to memorialize small moments spent prolonging America’s longest conflict can’t escape the same myopic approach we applied to fighting the war and “winning hearts and minds” in Afghanistan.

The same challenge coins I was given as a Marine can be bought for less than $2 on Chicken Street — if you’re a seasoned haggler and speak a little Dari. If you don’t, you’ll be treated the way all Americans have been treated by Afghans since 2001. “How much do you want to pay?” is the question almost all shopkeepers on Chicken Street know how to ask in English. They’re hoping that you’re a miniature version of the America they know: flush with cash, short on understanding, scared of the locals and eager to buy something to show for your time in their country. If they agree to the price you offer without any haggling, you’ve undoubtedly overpaid.