The Germans were caught completely by surprise with Operation Diadem. They believed the Allies were going to make an amphibious landing north of Rome, and they positioned their reserves accordingly. Subsequently, many key commanders and staff officers from units on the Gustav Line were in Rome on pass. Both Gens. Vietengoff and Senger, the repective German army and corps commanders at Cassino, were receiving medals from Hitler when the battle started. In fact, all of the German preparations on the Italian peninsula were in accordance with Allied intentions, as per their deception plan, Operation Nonton. Even worse, German planners made a critical assumption that turned out to be grossly naive: that if the Allies attacked the Gustav Line, they would only attack at Monte Cassino. Much to their later consternation, the Germans reinforced the area around the Monastety at the expense of the rest of the front.
That one bad assumption played right into the strengths of the various national armies. Along the coast, American tenacity and firepower, in the form of massed artillery, close air support, and naval gunfire, steadily reduced the strongpoints blocking their way. In the Auruncii Mountains, mountain expertise and espirit de corps allowed the Frenchmen, in particular the Goumiers, to negotiate terrain that no German ever considered passable. Entire platoons of Goumiers free climbed cliffs, draws, and stream banks, and they did it with 25kg packs. German positions were consistently outflanked and French troops seemed materialize out of the ground.
Along the Rapido River, the British penchant for preparation and organization to be “just so” was exactly what was needed for that most demanding and exacting of offensive operations: contested river crossings. By the night of 13 May, the 8th Indian Division had a solid bridgehead across the Rapido at San Angelo, in almost the exact same spot where the Texans of the US 36th Division were massacred four months before. That night they would pass a Canadian armored brigade over the river. It would soon push into the Liri Valley: treading where no Ally had treaded before.
Along Snakeshead Ridge, the Poles took horrendous casualties attacking the prepared and reinforced Fallschirmjaeger positions. They recklessly threw themselves into “the amphitheater” formed by the imposing heights that formed its rim: Point 593, Albaneta Farm and the Monastery. Despite neither cover nor concealment, they made great gains, on both slopes of Monstery Hill. They captured Cassino town and almost reached the Liri Valley north of the Abbey. The 3rd Carpathian Division even captured Pt 593, several times. However, most Polish maneuver battalions were at 50% strength by the end of the second day of fighting. Pt 593 needed to be consolidated to prevent its recapture, but unfortunately, the Green Devils immediately recognized the nature and importance of the Poles’ main objective and continued to feed its defense. A desperate final counterattack on the night of 13 May of just 14 remaining able bodied troops, led by the remaining instructors from the German parachute school, regained the crucial objective from its final seven Polish defenders.
The battle was coming down to whose mules could feed the battalions in the assault zones the fastest. The critical logistics calculus was changed not by the Poles, but by the British advance. Their bridgehead across the Rapido and into the Liri Valley allowed artillery to fire onto the hitherto protected German assembly areas and “forming up points” on the reverse slopes of the Albaneta Massif and Monte Calvario. For the first time in the battle, the Germans on Monte Cassino were receiving fire from directions and in areas they had not previously experienced. The limited German reserves were thrown at the Canadians and Indians pushing up the Liri Valley to fix their fires and protect their concentrations.
But the Germans also knew they would not hold Point 593 for long if the Poles held the gains they made. The Polish assault battalions were within meters of cutting off the star fort. They were temporarily spent and their gains exposed, but the Polish sense of duty and resilience would see them through. They burrowed into the shattered terrain and four months of dead bodies and awaited their mules and comrades. Gen Anders himself went to his support units for volunteers. Thousands put down their wrenches, typewriters, and ladles, picked up their rifles, and headed up the mountain. Even Private First Class Wotjek, the ursine ammo handler of 22 Artillery Company and II Polish Corps’ mascot, followed his comrades up the hill after they volunteered to fight as infantry. One way or another, the next attack would be the last.