When Hitler ordered Erwin Rommel to prepare for an Allied invasion of the north of France in 1944, the German field marshal found the defense of “the Atlantic Wall” deficient. Innovation and effort, Rommel concluded, would have to make up for a lack of manpower.

He had thousands of miles of barbed wire strung. He directed hundreds of thousands of tons of concrete poured to build bunkers to protect his machine gunners and artillery. He ordered more than 6 million mines buried along the beaches.

Perhaps the most unusual defense, and most recognizable because of its seeming omnipresence in photographs of D-Day, was a device nicknamed “the Czech hedgehog.”

Like an oversized caltrop, the hedgehog was designed to rip into the thin skin of lightly armored vehicles. Made from iron beams welded together into a sort of five-sided asterisk, it had another benefit: The hedgehog could be blown in any direction by an explosive and still land upright.

Rommel had thousands built, placing more than 1,000 at Omaha Beach alone. Personnel ships landing at high-tide would float over the submerged hedgehogs, slice open their bows, and spill their troops into the water. At least that was the plan.

The Allies landed at low tide instead, leaving the hedgehogs exposed in the sea. Pilots of the infamous “Higgins boats” sailed around them. Allied troops ran past them. They were largely ineffective.

Now some 75 years later, House Speaker Nancy Pelosi, D-Calif., wants to adopt the Nazi obstacles for the southern U.S. border.

“There is not going to be any wall money in the legislation,” Pelosi told reporters Thursday. Pelosi controls the House floor, and, as Susan Ferrechio of the Washington Examiner reports, Pelosi's approval of a border security deal is required for legislation to make it to the president’s desk by a Feb. 15 deadline.

[Read more: 'A WALL is a WALL': Trump mocks Congress for talking about fences, barriers]

Pelosi won’t budge on funding for the wall as envisioned by President Trump. As far as a physical barrier is concerned, the Normandy-style fencing is all that the speaker will support.

“If the president wants to call that a wall, he can call it a wall,” Pelosi said. “Are there places where enhanced fencing, Normandy fencing, will work? Let them have that discussion.”

Again, and as Ferrechio notes, this type of Normandy-style fencing is meant to stop vehicles, not people on foot. Currently, U.S. Border Patrol employs it to do exactly that. But even when welded together with rebar to create a sort of fence, the barriers are still very low.

As Allied forces learned in 1944, you can hop over them or walk around them.