Jon Hammar saw combat in Iraq and Afghanistan, but his most brutal foreign experience was in Mexico. Last August, the 27-year-old former Marine corporal was incarcerated by Mexican authorities in Matamoros for trying to register an antique shotgun with customs agents. Foolishly, Hammar followed instructions given to him by U.S. Border Patrol agents in Brownsville, Texas. He registered the gun with them and brought the paperwork to the Mexicans to get their stamp of approval in order to carry the gun through the country. Hammar and a friend were driving a Winnebago, hoping to have a nice surfing vacation with some hunting on the side.

Even though the Mexican authorities clearly saw that Hammar was trying to follow the rules, they seized the Winnebago and locked him up in the notoriously corrupt CEDES prison anyway. There he was threatened by other inmates and told by guards that he could buy his way out of the hellhole by paying money to the “right people.”

Hammar’s parents, who live in South Florida, immediately contacted the State Department and were told to be patient. Three months later, Hammar was still incarcerated and had not even seen a judge, and things were becoming increasingly desperate.

That’s when his parents gave up on the State Department and contacted the media.

U.S. Sen. Bill Nelson and Rep. Ileana Ros-Lehtinen raised some hell about the situation, but things continued to deteriorate. Mexican authorities actually chained Hammar to his bed. Another inmate sent a picture of that out to the press.

Neither President Obama nor Secretary of State Hillary Clinton had come to the aid of an American combat veteran who was being abused by Mexican authorities.

Disgusted by our apathetic government and on national television, I told the new Mexican president, Enrique Pena Nieto, that if he did not release Hammar by Christmas, I would lead a boycott of Mexican tourism and products. The next day, Hammar was released after a Mexican judge ruled there had been no intent to commit a crime.

The ordeal cost the Hammar family tens of thousands of dollars in legal fees and untold emotional damage. Thankfully, Hammer did arrive home in time to have a nice Christmas with his family. But this story is a cautionary tale for any American traveling outside the U.S.

If you get into trouble, you will be essentially on your own. Our leaders in Washington are basically bureaucrats with short attention spans. If they couldn’t work up the energy to help Jon Hammar, they are not going to help you.

As for Mexico, it remains a corrupt country hostile to the rule of law. Let the buyer beware.

Bill O’Reilly is host of the Fox News show “The O’Reilly Factor.”