Enabling the Joint Offense – The 1945 Okinawa Campaign Success at Luzon in 1945 postured the U.S. to continue “island hopping” into Okinawa, the largest of the Ryukyu islands, and deep within Japanese territory. The Japanese accordingly prepared a defense in depth to delay, rather than destroy, U.S. forces until planes could sink U.S. naval support and isolate the beach- head.14 Japanese defenders dug into strongpoints in restrictive terrain to pro- tect themselves from substantial naval and aerial bombardment. The American response was the early projection and asymmetrical use of armor in tank-in- fantry teams during the forcible entry, through the extension of the beachhead, and to the ultimate seizure of the island.15


Outlined in FM 3-0, the maritime oper- ational consideration of “defeating com- ponents of enemy anti-access and area denial to enable joint offensive operations” specifically highlights Army forcible entry (airborne, air assault, ground, or amphi- bious) as setting the conditions for follow -on operations.16 In Okinawa, U.S. planners opted to conduct an amphibious landing on the Hagushi beaches as their forcible entry. Leading the landing forces, the 776th Amphibian Tank Battalion provided con- siderable fire support to the infantry establishing the lodgment.


Veterans of previous amphibious land- ings, the 776th employed practiced tactics on Okinawa. Specifically, the 776th de- ployed from landing ship tanks (LST) from five kilometers offshore ahead of the infantry and under naval fires. They then bounded from their LST to their objective line 400m inland and established support by fire positions.17 The rapid maneuver accomplished two key functions: first, it drew Japanese fires away from the vul- nerable infantry debarking transports, and second, it positioned the tanks to provide fires further inland as the infantry prepared to expand the beachhead.18 These sup- porting fires often functioned as short -range indirect fires, in lieu of artillery which shaped the deep fight. Like artil- lery call-for-fire, infantry requested miss- ions from the 776th to enable their advance. At Hagushi, and in subsequent operations, the 776th fired 41,297 main gun rounds to shape close and enable success through- out the campaign.19


24


Defeating area denial in forcible entries generally requires expansion of the beach- head to stabilize the lodgment. FM 3-0 specifies stabilization immediately follow- ing the assault phase of the amphibious landing and includes expansion from the shore to the island interior.20 Similarly, U.S. forces in 1945 expanded their lodg- ment on Okinawa, but required the mobility, protection, and firepower of armor to pene- trate a staunch defense at the province of Shuri.


The historic province centered around a Japanese castle with thick walls and integrated mountainous terrain, provided phenomenal obstacles, both natural and manmade, as well as a restricted and canalizing avenue of approach from the U.S. landing in the north. Its defenders created a defense belt of camouflaged and dugout positions. Reminiscent of Luzon, mutually supporting pillboxes, fortified caves, and entrenched guns, established a reverse slope defense.21 The result was a multi-layered and hidden defense that was largely protected from U.S. air and maritime superiority. Between the naturally limiting trajectory of a reverse slope and the deep digging, the protec- tive positions proved so effective that during one forty-minute concentration of fires from eighteen ships and twenty -seven artillery battalions “had not killed more than 190.”22 Paired with the defend- er’s massing of fires as U.S. forces crested the ridgeline, forced the offense into a stalemate.


Again, the American solution was the tank-infantry team under shaping indi- rect fires, and an asymmetric applica- tion of tank direct fire. U.S. artillery fires shelled Japanese positions to limit their visibility or force them underground for


protection. Tanks then assaulted, with securing infantry, and fired directly into the openings of the positions (see Figure 3). As the process gained traction and de- stroyed key components of the defensive belt, supporting infantry neutralized de- fenders attempting to swarm the tanks.23 However, as the reverse slope gave way to wider fields of fire, the Japanese massed indirect fires against tanks, separating the infantry support to isolate the armor. In response the U.S. rapidly task-orga- nized and employed the 711th Tank Bat- talion in a feint, drawing all Japanese fires against them, and enabling the adjacent infantry to envelop the positions from the rear.24 These tactics broke the Shuri line stalemate and facilitated the expansion of the lodgment and the transition to offen- sive operations.25


Throughout the Okinawa campaign, U.S. mounted forces were essential in the for- cible entry, expansion of the lodgment, and the defeat of area denial systems. In each instance, they deployed early, often ahead of infantry, and fought asymmetri- cally to gain tactical advantage in unex- pected ways. Providing indirect fires, protecting infantry as “mobile pillboxes,” drawing enemy fires, and knocking strong- points provided the asymmetric advantage needed to take Okinawa, and a pertinent lesson for modern application in the Indo -Pacific.26


Defend and Control Key Terrain – The 1966 Vietnam Challenge Decades after its forays through the Philippines, Japan, and Korea, U.S. armor returned to action in the Indo-Pacific in 1965 in Vietnam. American military con- ceptions of jungle fighting, largely derived from the Korean War, understood the ter- rain as unsuitable for armored formations,


Figure 3: Tanks were instrumental in the destruction of trenched gun positions.37 CAVALRY & ARMOR JOURNAL Fall 2024


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