American tanks in World War II were generally inferior to their German counterparts. German tanks boasted better armor protection and more firepower.

But armor and lethality don’t tell the whole story. The same American tanks were superior to their rivals in other important ways. The M-4 Sherman, in particular, helped the U.S. Army win the war—even though, in battle, German tanks destroyed them en masse.

The Sherman’s inadequacies were products of its origins. Before the war, American tank design and development was bipolar—a result of the competing demands of the Army’s infantry and cavalry branches.

The infantry wanted a tank that—no surprise—could support the infantry on the battlefield. Infantry generals favored a vehicle with a big gun that could sit still and take out enemy bunkers.

The infantry walked into combat. They weren’t all that concerned about a tank’s speed.

By contrast, the cavalry—the Army’s scouts—preferred a fast-moving tank that could speed through gaps in enemy lines. The freewheeling cav didn’t fret armor protection.

Two tank philosophies, totally at odds with each other. And the Great Depression exacerbated the problem—the R&D money ran out.

The American tank force idled until the war jumpstarted it.