M7 Priest — America Establishes Armored Artillery

By Richard Johnson Posted in #History

Thundering onto the battlefields of World War II, the M7 Priest married firepower with mobility at a time when the conflict’s outcome hung in the balance. From the deserts of North Africa to the jungles of the South Pacific, the M7 105mm self-propelled artillery (SPA) developed and refined techniques that are still used by the American military today.

While these tracked howitzers brought a great deal of versatility to the field, things were not perfect. Many commanders didn’t understand their usefulness and underutilized them. Often, the units were deployed close to the front lines and without adequate support to ensure security.

Nevertheless, the M7 Priests and their crews served with distinction, excelled at roles they were never intended for, and helped ensure a global Allied victory.

New Concept: Armored Artillery

While artillery was not new, the concept of armored artillery was. The general idea was to develop self-propelled guns that could support tanks. That meant the artillery had to be fast-moving and flexible, operate close to the front lines, and traverse terrain that would be impossible for towed artillery. Armored artillery needed to support breakthroughs, so they had to be self-sufficient and not bound to slow-moving supply lines.

Initially, the United States experimented with the T19 howitzer motor carriage: an M3 half-track with a 105 mm howitzer. Less than 350 of these were made and served in North Africa. However, they did not live up to the expectations of most commanders. Some were used in the Italian Campaign, and a very few would see service in France.

Developed at about the same time was a fully tracked vehicle that would become the M7 Priest. Using the same medium tank chassis as the M3 Lee tank, the M7 mounted a 105 mm howitzer in an open top, armored compartment. Later versions of the M7 would use the M4 tank chassis and were designated M7B1. Most documentation I’ve seen puts production at 3,490 M7 vehicles and 826 M7B1 variants.

In addition to providing a greater ability to navigate terrain compared to the T19, the M7 had enough room in the armored compartment for all crew members needed to operate the gun, radio equipment and 69 rounds of 105 mm. A small trailer could be attached to the M7 for an additional 42 rounds. Halftracks assigned to the battalions also carried 105mm shells to keep the Priests fed.

Light armor protected the crew from small arms, most machine guns and shell fragments. While not as thick as a tank, the armor did a fair job of protecting the men and allowing them to run the guns even when under fire. And for units operating close to the front lines, this was important.

Each Priest was equipped with an air-cooled M2 .50-caliber machine gun. While this was very effective against enemy infantry and vehicles in close contact, it was designed for air defense. Each man on an M7 crew trained with the M2 and received aircraft recognition training.

Every battery of an armored artillery battalion was authorized for six M7 Priests. Arranged in a hexagonal pattern, the configuration allowed the battery to deliver rounds on target with fewer adjustments. The result was a 50% increase in firepower compared to standard infantry artillery units, which were assigned only four guns per battery.

Mobility of these vehicles was said to be very good — roughly equal to the medium tanks of the time. Many officers and crews commented during and after the war that they could get the M7 places that would have been impossible for traditional towed artillery.

Lt. Col. Hugh M. Exton, FA, in the May-June 1948 article in The Field Artillery Journal stated, “During this landing [at Sicily], it was observed that the vehicles which moved across the beaches with the greatest ease were the DUKWs and the M-7s (sic).”

This was echoed by Maj. Edward A. Raymond, FA in his 1944 article “As Skirmishers.” “The…M7 proved a superior landing vehicle,” he said about the invasion of Sicily. “It could be debarked in…water and still come ashore under its own power. It could operate over soft sand, and negotiate extremely difficult beach exits. Being able to fire without the delay of going into a position, it was able to furnish immediate support as soon as it reached the beach.”

One of the key things about the M7 is that when it gets close to the enemy, it has everything it needs to go into action quickly. This allows it to “shoot and scoot” to support advancing troops. Being close to front allowed for increased accuracy on moving targets since there was less flight time.

The M7’s mobility also allowed it to pull out at a moment’s notice to avoid counterbattery fire. This mobility proved useful when crews were under threat of being overrun. Crews could pull back or quickly redeploy for direct fire.

Of course, no weapon system is perfect. The M7 had two primary issues, and both dealt with the howitzer’s placement in the vehicle. First, the angle of elevation was limited: -5˚ to +35˚. This sometimes created an issue when firing in dense forests. Gunners had to have enough clearance to get over any trees close to their firing position.

A second issue was with the angle of traverse. The angle of traverse was relatively small — 15˚ left and 30˚ right — meaning vehicle repositioning would be required if a significant shift was needed. According to some of the after-action reports I’ve read, good coordination between the driver and crew leader could minimize the issue.

Who Used the M7?

The primary user of the M7 during World War II was the United States Army. The Army used the M7 extensively in Africa and Europe. Later in the war, the Army increased its use of the M7 Priest in the Pacific. More on that below.

The U.S. Marine Corps used relatively small numbers of the M7 in the Pacific, often using them as assault guns to directly support infantry.

A limited number of Priests were used by British forces. After the war, the M7 Priest was sold or given to various American allies, including Israel and West Germany.

Underutilized by Commanders

Despite the benefits mobile, lightly armored artillery offered, many commanders did not seem to appreciate its usefulness when developing battle plans. Near the beginning of the war, none other than Gen. George S. Patton is quoted as saying:

“By methods known only to God and the artillery, fire was placed on the target.”

It’s not that commanders didn’t appreciate the value of artillery. I imagine it was quite the opposite since so many had served in World War I and had been on the receiving end of a fair amount of it. Rather, it was the mobility of armored artillery that many did not fully grasp and exploit.

In his 1949 article “Armored Artillery in the Team,” Maj. Ralph M. Click stated that there was a “mystery surrounding field artillery techniques” that “caused many commanders at all levels to fail to fully realize the tremendous fire potential of their supporting artillery.” Consequently, “the artillery’s fire power was not integrated into their planning except in the most general terms.”

Nevertheless, the M7 Priest proved its worth from Tunisia to Berlin.

In the March 1943 issue of Firepower, the Ordnance Department of the U.S. Army stated “…the M-7s (sic) played a substantial part in breaking the back of Rommel’s army. Rolling along at better than 35 miles an hour, they would suddenly stop to hurl high-explosive and armor-piercing shells more than seven miles against enemy tanks, guns, supply columns, and troop positions.” According to the editors, captured Italian and German soldiers stated this artillery was “bewildering” and it was due to the constant shelling from the M7 Priests “…that you managed to beat us.”

With extensive experience in North Africa, Sicily and Italy, both commanders and M7 crews were better prepared to exploit the Priest’s advantages when the Allies landed in Normandy.

M7 Priest during Operation Overlord

The M7 Priest proved its combat value prior to the Normandy landings. Combined with its excellent performance on the beaches at Sicily, it’s not surprising that the M7 was a key player when invading Fortress Europe.

Maj. Gen. H. W. Blakeley commanded the 4^th Infantry Division Artillery on June 6, 1944. Under his command were three infantry artillery battalions and one armored artillery battalion. All of the units were equipped with the M7 Priest. Gen. Blakely stated in 1946, “We had long training with them and they were highly satisfactory.”

As mentioned previously, the infantry artillery batteries were assigned only four M7 Priests as opposed to the six in armored artillery batteries. But it did not always remain that way once in the field.

The 29^th Infantry Artillery Battalion lost an entire battery of four Priests during the invasion when their LCT sank on the way to Utah Beach. They were replaced on D+3. However, instead of reconstituting the third battery, Gen. Blakely assigned two M7s to each of the first two batteries. This made the 29^th’s batteries equivalent to those of the armored artillery. Gen. Blakely stated he preferred this deployment.

While the other artillery battalions retained their M7s, the 29^th later had them taken away for use elsewhere. Standard towed 105 mm howitzers were used to replace them. Gen. Blakely stated he spoke to all 12 crews in the 29^th, and every man expressed a strong preference for the M7.

The 78^th Commandos

Rivalries between units are likely to have existed since the earliest organized armies. The American units in World War II were no exception. One incident between M7 Priests and M4 Shermans happened in the Fall of 1944. 

During combat around the Siegried Line, the 78^th Armored Artillery Battalion advanced to a position it believed was about 500-1,000 yards behind the front line. Unknowingly, the artillery battalion outpaced the 67^th Armor Regiment that it was supporting and set up almost on top of an enemy German unit. It wasn’t until the 67^th Armor showed up and engaged the Germans on its doorstep that the artillery battalion realized it had leapt too far forward.

When the 78^th commander later entered the 2d Armored Division HQ, Brig. Gen. Isaac D. White told him, “I’ve just received a complaint about your outfit from the 67^th. It seems they were all set to overrun and clean out an area, but when they arrived at it, there was your unit in position. They say you’re violating union rules in capturing ground they were charged with taking.” From that point forward, the battalion was given the nickname of the “78^th Commandos”.

While this near-disastrous incident is humorous in hindsight, M7 Priest units did their fair share of direct combat throughout the war. And they often gave better than they got.

Not Tank Destroyers, But Can Do When Needed

The M7 Priest was self-propelled artillery, and it was never considered a true tank destroyer like the M10 “Wolverine” or M36 “Jackson”. Even so, there was enough confusion about this that multiple sources published statements to clarify the issue.

In his article, “As Skirmishers” in the August 1944 issue of The Field Artillery Journal, Maj. Edward A. Raymond, FA, stated, “Popular magazine advertisements to the contrary notwithstanding, M7s are unequal to slugging it out with tanks in the open at pointblank range.”

In the January 1944 issue of The Field Artillery Journal, the editors published the following statement:

“Newspapers to the contrary notwithstanding, the M7 Motor Carriage is not a Tank Destroyer. Both design and tactics take it out of that group. Any field piece may fire against tanks, but is not ipso facto a Tank Destroyer.”

Part of the confusion is likely from print advertisements. At least one colorful, victory-style print ad ran showing the M7 Priest as a tank destroyer.

Another ad published by American Locomotive described the M7 as the “tank killer that helped turn the tide at El Alamein.” Further, this advertisement stated, “It was then called, technically, the M-7 (sic). In its baptism of fire, it was given the much more descriptive name of ‘tank killer’.”

Of course, it didn’t help that the previously referenced story about the M7 Priest in the 1943 issue of Firepower was titled “Tank Destroyers.” Even The Field Artillery Journal, in its March 1943 issue, stated that the M7 was the “scourge of Nazi tanks.”

Nevertheless, the Priest was capable of defending itself against tanks in direct action.

“All armored artillery must be able to defend itself against any tank attack,” said Capt. Curtis K. Allen, FA, in his March 1944 article “Armored Artillery and Direct Fire” published in The Field Artillery Journal. “A gun crew is not properly trained if it cannot hit any tank, at a reasonable speed, at any range up to 1,500 yards for the third round.” Further, he said: “Making the first shot a target hit should be the rule, not the exception.”

There are numerous examples of the M7 Priest deployed for direct action against armored units. Several such actions occurred during Operation Cobra — the Allied offensive to break out of the Normandy region of France.

Lt. Col. Hugh M. Exton, FA, detailed one of these incidents in his series, “Morocco to Berlin” published in The Field Artillery Journal, May-June 1948. During a fierce German counterattack, the 78^th Armored Field Artillery Battalion moved into positions that allowed them to fire directly down a road that was a likely route for a German counterattack. During the night, a German column attempted to overrun the 78^th. However, the American crews fought hard and, by the morning, the German column had been destroyed. Survivors pulled back, leaving 20 burning tanks and armored vehicles behind.

Follow-on indirect fire from the 78^th resulted in the destruction of 96 additional vehicles and the death of approximately 1,200 German soldiers. Lt. Col. Exton stated that combined, the actions of the 78^th Armored Artillery Battalion “destroyed the remnants of the German 2d SS “Das Reich” Panzer Division.” Unfortunately, the SS division would be rebuilt and return to combat U.S. troops in the Ardennes.

Lt. Col. Edward S. Berry, FA stated that while Allied troops were trying to close the Falaise Pocket during Operation Cobra, “Three enemy tanks attacked the flanks of [another artillery unit’s] position. One attacked Battery C, destroying an ammunition trailer and damaging an M7, which was put out of action. Another of our M7s took the tank under fire with a HEAT shell and destroyed it.”

Maybe the M7 couldn’t go toe-to-toe with tanks on open ground, but they had teeth. In an ambush situation, they could be just as effective as an anti-tank unit. When pressed, they made the enemy pay dearly for any gains it hoped to make.

Fighting as Infantry

While it might seem that all members of the U.S. Army should have received combat infantry training, that was not the case during World War II. Instead, artillerymen were given only basic instruction with carbines, rifles and machine guns. They were not taught infantry tactics.

“Other specialized arms — the Coast Artillery Corps and the Engineer Corps, for example — are taught infantry tactics in addition to training in their own branch,” said Maj. Edward A. Raymond. “Three campaigns against the Nazis are showing the Field Artillery the wisdom of that course.”

The three campaigns he discussed — North Africa, Sicily and Italy — each had numerous examples of armored artillery units dismounting and defending themselves against attacks that broke through the front lines. Yet, these men did not have basic training on infantry tactics.

Early on, two-thirds of the crewmen were armed with the .45-caliber M1928 submachine gun, better known as the Tommy Gun. The remaining soldiers were armed with the M1911 pistol. Later, some crews would be issued the M3 submachine gun instead of the Thompson. I’ve read several accounts of pistol-equipped crewmen acquiring other firearms, including the M3 and .30 caliber M1 Carbines, to improve their capabilities. But the equipment wasn’t enough.

“The training of artillery organizations for infantry combat is left to the responsibility of unit officers and NCOs,” said Maj. Edward A. Raymond, FA in “As Skirmishers.” “We train our men to handle infantry weapons; we have not trained their leaders to handle their men as infantry.”

Some officers recognized the deficiency and the danger it caused. They undertook training the men, and it paid off when needed. Numerous times in Tunisia, Italy, France and Germany, M7 crews dismounted to engage the enemy.

In one such incident, a 4^th Infantry Division outpost was overrun, putting German troops on the doorstep of the 78^th Armored Artillery Battalion. The 78^th took direct-fire positions, and all support personnel deployed as infantry to repel the attack. A close-quarters battle ensued with a great deal of small arms fire and grenades thrown. The M7s engaged German tanks. It was hard fought, but the artillery battalion stopped the German advance, knocking out seven German tanks and killing 126 German soldiers.

Another incident was documented in “Artillery in an Encirclement” in the February 1946 issue of The Field Artillery Journal:

“This battery [of M7 Priests] in position covering a bridge was firing on 20 German Pz Kw IV tanks and a force of 300 motorized infantry. Early in the afternoon with approximately 200 enemy infantry flanking the battery position Lt. Carr, in the absence of the battery commander, ordered his cannoneers, drivers, and wire section to take up positions around the battery and drive off the enemy, leaving the First Sergeant and Chiefs of Section to serve the pieces. By use of .50-caliber machine guns and rifles the battery personnel successfully forced the enemy infantry to withdraw and the battery continued heavy and destructive fire on the enemy tanks.”

Lt. Carr had trained his men in infantry tactics, and it seems they paid off. The M7 battery lost only two men, and the German attack was stopped cold.

Assault Guns in the Pacific Theater

While there were limited uses of the M7 as an assault gun in the ETO, it was the Pacific Theater where the artillery piece made a real impact as a direct fire weapon.

As has been well documented in our articles about the invasion of Iwo Jima and the combat on Peleliu, Japanese defenders were tenacious in their defense against American troops. Pill boxes and other hardened positions made fighting extremely tough for U.S. soldiers and Marines. U.S. troops with flamethrowers helped, but big guns were also useful.

The M7 Priest worked well as an assault gun in these island campaigns. As European troops discovered, the Priest could navigate beaches and other terrain very well. And with fewer tanks to defend against, the M7s’ armor offered fairly good protection for their crews. This allowed the Priest to support infantry by blasting machine gun nests and pillboxes.

Korean War

Entering the Korean War, the United States still relied on the M7 and M7B1 variants. However, the limited angle of elevation quickly became an issue when fighting in mountainous regions. Enter the M7B2.

To overcome the elevation limit, the Army modified 127 M7B1 Priests to increase the angle of elevation to 65˚. This modification required the M2 machine gun mount to be raised to retain the ability to engage targets at a full 360˚.

Final Thoughts

The M7 Priest was not the first attempt to mount a cannon on a mobile platform. But it did prove to be a decisive weapon platform for the Americans during World War II. It proved that artillery could work with rapidly moving tank attacks, offering significant flexibility on a dynamic battlefield.

The Priest was widely liked by the troops who used it, and it was those men who helped establish artillery tactics and doctrine that would continue to evolve during the next 80+ years.

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