D-Day gave us duck boats. The 21st century military might provide new ways to get around, too.

Globe Staff

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The boat was so old that, we joked, it was probably used on D-Day.

Here’s the kicker: the Cape Henlopen, a car ferry that I worked on in high school that is still afloat today in Long Island Sound, actually was part of the Allied invasion of France in 1944.

The massive landing involved 7,000 ships of various sizes. After the war, the military quickly got rid of most of them. Other D-Day craft found new uses — including, infamously, as duck boats for tourists in Boston and other cities.

Of course, there are plenty of military investments that ended up yielding much more important civilian uses — radar and the Internet, for instance. Civilians piggybacking on military products and innovations is an age-old story.

But that ferry, which was built for basically one day of military use and then yielded decades of public benefit, sticks in my mind as a symbol of just how great the payoff can be.

Soldiers unloaded equipment on Omaha Beach in Normandy on D-Day – June 6, 1944.HO/AFP/Getty Images

Currently, the military has thousands of vehicles, including 170,000 “non-tactical” vehicles like cars and trucks. Electrifying that fleet would put the Pentagon’s enormous buying power behind EVs and make building out the nation’s charging infrastructure a matter of military necessity.

But what’s more interesting to me is how the military approaches sophisticated combat equipment, stuff like tanks and fighter jets — because that’s where there’s opportunity for military innovations to spill back into the civilian world and help the fight against climate change. (The military has already created one possible decarbonization option: nuclear-powered vessels, which could reduce the enormous environmental impact of commercial shipping.)

That’s the direction in which the Pentagon appears to be heading. The Army intends to “electrify the battlespace,” Lieutenant General Duane A. Gamble told Congress in 2021. The Air Force has backed experiments with synthetic aviation fuel.

The purpose of those investments is to win wars, not necessarily to reduce greenhouse gas emissions: Gamble noted that electrifying tactical vehicles had various potential benefits for the Army, including reducing maintenance and logistics costs and giving vehicles “reduced thermal and acoustic signatures” that make them harder for an enemy to detect. Moving away from traditional fuels could also save lives; according to the Air Force, at one point 30 percent of the US casualties in the Afghanistan war occurred because of attacks on fuel and water convoys.

In those investments, though, there could be huge implications for how the rest of us get around. Someday, when some future teenager gets a job on a battery-powered boat, he might have the Pentagon to thank.