The British and Americans knew the destruction of the Abbey at Monte Cassino in February changed the calculus of the battle, though they did not realize its extent. The key to the Liri Valley and Route 6 to Rome was the town of Cassino; the key to Cassino was Castle Hill, the key to Castle Hill was Hangman’s Hill; and the key to Hangman’s Hill was the Abbey itself. Since the clumsy and brutish destruction of the Abbey allowed the Germans to fortify it, the Brits and Americans assumed that it needed to be the focus of the battle. But as the Germans suspected, and the Italians knew, that this was not the case: the key to the Abbey was actually Point 593, which was a small hillock just to the northwest on Snakeshead Ridge.
In the previous three battles, a supporting attack was always launched against Pt 593, but only to prevent enfilading fire on the main attack or tie down counterattack forces, not to capture it. When the Polish II Corps received the mission to take the Abbey, the corps’s staff naturally started its mission analysis. During their initial intelligence preparation of the battlefield, a young analyst did his research on the area and noticed the ruins of a small 17th century Papal star fort on Pt 593. But why was that star fort in such an inaccessible location? Digging into the history of the area for the answer, he found that the star fort (and presumably the earlier medieval keep ruins beneath it) provided a last desperate refuge for the monks during Italy’s turbulent past. Control of the star fort by the monks ensured that if it wasn’t also captured, the Abbey was untenable. The analyst studied the terrain further and found that the Allies could reverse engineer the battle: If Pt 593 fell, the Abbey would fall; if the Abbey fell, Hangman’s Hill would fall; if Hangman’s Hill fell, Castle Hill would fall; if the Castle fell, Cassino would fall. And if Cassino fell, the Road to Rome through the Liri Valley was open.
So think of the Abbey as a typical suburban American house. The star fort on Point 593 was (and still is) a sort of combination storage shed and fortified zombie apocalypse safehouse in the back corner of the monastery backyard. Also, it butt’s up against the back fence (Snakeshead ridge), so unless you climb over the back fence, you can’t approach the shed (Pt 593) except through the house (the Abbey).
In that context, think of the Liri Valley as the street the house is on. Throughout the Monastery’s 1500 year history, any army wishing to drive down the street, i.e. exit or enter the Liri Valley to capture Naples or Rome, had to secure the Monstaery because it dominated traffic on the street. To do this some secured Papal approval because the Monastery was property of the Papal States, governed directly by the Roman Catholic Church. But most chose to capture the Abbey.
These historic encounters usually followed a similar pattern. The attackers would initially try storming the hill, and inevitably fail. There would then be a siege. Shortly thereafter, the attackers would get restless because they were wasting time and resources on the Monastery that would be required for use on Rome or Naples. So they would get impatient and launch multiple costly assaults, which would wear down the monks and their defenders. When capture was imminent, the monks would then retire to the small fortress on Pt 593 and the attackers would flood victoriously into the Monastery. That was, until they got into the backyard and were stopped cold by the defenders on Pt 593. The star fort on Pt 593 made the northwest corner of the abbey untenable and the space between the monastery and the fort a killing ground, i.e. the backyard in our house simile.
Now here’s the true genius of Pt 593: Occupying it could only tangentially affected the Liri Valley. Attackers that captured the monastery but not Pt. 593 could enter and exit the Liri Valley at will, even with the monks still occupying the back corner of the backyard. However, it was to the backyard of the Monastery what the Monastery was to the Liri Valley: As the Monastery made passage in the Valley difficult, Pt 593 made the northwest portion of the Monastery grounds untenable. So naturally, the attackers looked at Pt 593, then looked at the valley, then looked back at Pt 593 and said, “Screw this, I’m not attacking that, I’m done with this place. We need to move onto Rome (or Naples).” And the invaders would invariably move on to Rome or Naples, and leave a token force to keep the monks isolated in the star fort. This was the signal for the monks to make the attackers lives miserable until they either left, or were weakened sufficiently that the monks could burst forth from Pt 593 and slaughter them. In either case, the monks would then reclaim the Abbey, clean up the debris, restock the library, and resume the Rule of St Benedict, at least until someone else wanted to enter or exit the Liri Valley without the Pope’s permission.
In the mid twentieth century, this all changed. Modern engineering, improved and efficient aerial and ground logistics, proper reconnaissance and modern firepower lessened the formidability of the terrain. Snakehead Ridge was still impassable to vehicles and even to mules in some places, but the French in January proved that that was no barrier to a successful assault, if you had prepared properly, conducted a sufficient recce, surprised your enemy, had a touch of élan, and most importantly, threw a ton of soldiers at it.
To deceive the Germans, the Polish II Corps planned to execute the same plan as the Indians and Kiwis before them. But since they had a larger force along the same frontage, they would weigh the attack on Pt 593 from over Snakeshead Ridge, thereby breaking the historic cycle, by taking Pt 593 before the Abbey. As the monks knew, this would make the backyard and NW side of the Abbey untenable, but this time not for the attackers, but for the defenders, the Germans.
The young Polish analyst presented his findings, and the Corps operations officer issued initial reconnaissance guidance to confirm it. Unfortunately, the Poles were not yet in the line at Cassino and moreover, Operation Nunton forbade any patrolling to minimize the risk of capture. But MajGen Wladyslaw Anders, the Polish II Corps’ Commander, was so intrigued with the information that on 5 April 1944, he personally undertook a dangerous low level aerial reconnaissance of the area. Though he was nearly killed for his efforts, he confirmed the analyst’s assessment and issued his commander’s planning guidance accordingly. Disconcertingly, he found that the Germans turned the area around the ruins of the star fort in a hellish maze of mines, wire, interlocking fields of fire, and preregistered artillery. On the other hand, he also saw it was possible, if improbable, to capture Pt 593 from the north and northeast, but only if the attack was properly planned and coordinated. Unlike the Americans, the British, the Indians, and the Kiwis; the Poles’ main objective during the Battle for Monte Cassino would be Point 593, not the Monastery itself.