On the major European and Russian fronts throughout World War II, the challenge of crossing rivers and other water obstacles under fire was absolutely central to any advance. The Panzers that crossed the Meuse at Sedan in May 1940 cut the French Army in two; the Wehrmacht's ability to cross the great rivers of the western USSR was vital to the lightning advances of Operation Barbarossa in 1941, and in 1943-45 the Red Army had to drive the Germans back from a succession of river lines during their advance to the Reich, culminating in the Vistula and Oder lines; in Italy the Rapido formed a...

In 1965, soon after the first US combat troops had arrived in Vietnam, it was realized that in some areas the Viet Cong had developed vast tunnel complexes in which to hide from the enemy. It was long known that such complexes existed, but it was not realized just how extensive they were in some areas, how important they were to the Viet Cong, and how difficult it was to detect and neutralize them.

Most complexes were not nearly as developed and extensive as the famous tunnels of Cu Chi, but nonetheless they caused difficulties for Free World Forces. Tunnels served as hiding places...

The cavalry regiments of the US Army were in the process of being transformed into a mechanized force when the USA entered World War II. While those cavalry regiments deployed to the Pacific to fight the Japanese were turned into infantry units, those sent to Europe were employed as light armor in the cavalry's traditional spearhead roles - reconnaissance, the screening of advances and flanks, and the pursuit of beaten enemy forces.

Equipped with M8 Greyhound armored cars, M5 Stuart and M24 Chaffee light tanks, and halftracks, these units were designated cavalry groups (mechanized),...