M1 Mortar (US)

 

US Army 81-mm mortar crew in North Africa, 1943.

The M1 mortar is an American 81 millimeter caliber mortar. It was based on the French Brandt mortar. The M1 mortar was used from before World War II until the 1950s when it was replaced by the lighter and longer ranged M29 mortar.

General Data

Type: Infantry mortar

Place of origin: United States

In service: 1935–1952

Used by:

United States

Vietnam

Other users

Wars:

World War II

Korean War

Algerian War

Vietnam War

Nicaraguan Revolution

Salvadoran Civil War

Weight:

Tube 44.5 lb (20 kg)

Mount 46.5 lb (21 kg)

Base plate 45 lb (20 kg)

Total 136 pounds (62 kg)

Length: 3 ft 11 in (1.19 m)

Crew: 8 (squad leader, gunner, assistant gunner, 5 ammunition bearers)

Caliber: 81 mm (3.2 in)

Rate of fire:

18 rpm sustained

30-35 rpm maximum

Muzzle velocity: 700 ft/s (210 m/s)

Maximum firing range: 3,300 yd (3,000 m)

Sights: M4

Ammunition

M43A1 light HE: 7.05 lb (3.20 kg); HE filling 1.22 lb (0.55 kg); range min 100 yd (91 m); range max 3300 yd (zone 7, 3018 m); 80% frag radius 25 yd (23 m) (compared favorably with the 75 mm howitzer). M52 superquick fuze (explode on surface).

M43A1 light training: an empty version of the M43A1 light HE with an inert fuze. It was used as a training shell until it was replaced by the M68 training practice shell.

M45 heavy HE: 15.10 lb (6.85 kg); HE filling 4.48 lb (2.03 kg); range max 1275 yd (zone 5, 1166 m); bursting radius comparable to the 105 mm howitzer. Equipped with M45 (super quick/delay action selective) or M53 (delay action only) P.D. fuze.

M56 heavy HE: 10.77 lb (4.86 kg); HE filling 4.31 lb (1.96 kg); range max 2655 yd (zone 5, 2428 m), standard for issue and manufacture shell replacing M45. It used the M53 fuze back in 1944, but it was at some point replaced by the M77 Timed Super Quick (TSQ) fuze.

M57 WP (white phosphorus) "bursting smoke": 10.74 lb (4.87 kg); range max 2470 yd (2260 m); designed to lay down screening smoke, but had definite anti-personnel and incendiary applications.

M57 FS (a solution of sulfur trioxide in chlorosulfonic acid) chemical smoke: 10.74 lb (4.87 kg), range max 2470 yd (2260 m); laid down dense white fog consisting of small droplets of hydrochloric and sulfuric acids. In moderate concentrations, it is highly irritating to the eyes, nose, and skin.

M68 training practice: 9.50 lb to 10.10 lb. An inert teardrop-shaped cast iron shell without provision for a fuze well that was used to simulate the M43 light HE shell. The casing on early models was painted black but post-World War 2 versions are painted blue. It came in 9 different weights (engraved on the shell) to allow it to simulate shell firing with and without booster charges. Weight zone one (9.5 lbs.) simulated a shell with the maximum of 8 booster charges and weight zone nine (10.10 lbs.) simulated the shell being fired without booster charges.

M301 illuminating shell: range max 2200 yd (2012 m); attached to parachute; burned brightly (275,000 candelas) for about 60 seconds, illuminating an area of about 150 yards (137 m) diameter. It used the M84 time fuze, which was adjustable from 5 to 25 seconds before priming charge detonated, releasing the illuminator and chute.

Fuzes

The M1 mortar's shells sometimes used the same fuzes as the shells for the M2 60 mm mortar. An adapter collar was added to the smaller fuzes to allow them to fit the larger shells.

M43 mechanical timing (MT) fuze: clockwork timed delay fuze. Models M43A5.

M45 point detonating (PD) fuze: selective fuze that could be set for time delay or super-quick (less than a second) detonation on impact. Replaced by the M52 and M53 fuzes.

M48 point detonating (PD) fuze: selective powder train burning fuze that can be set to super quick or delay ignition on impact. The factory pre-set delay time was stamped on the shell body. If the super-quick flash ignition failed, the delay fuse kicked in. If set on delay, the super-quick flash igniter mechanism was immobilized to prevent premature ignition. Models: M48, M48A1, M48A2 (either 0.05 or 0.15 second Delay), & M48A3 (0.05 second delay).

M51 point detonating (PD) fuze: selective powder train burning fuze that can be set to super quick or delay ignition after impact. It is a modification of the M48 fuze with the addition of a booster charge. Models: M51A4, M51A5 (M48A3 Fuze with M21A4 booster).

M52 point detonating super-quick (PDSQ) fuze: super-quick fuze that activates less than a second after impact. The pre-war M52 was made of aluminum, the M52B1 model was made of Bakelite, and the M52B2 model had a Bakelite body and an aluminum head; the suffix would be added to the shell designation.

M53 point detonating delay (PDD) fuze: delay fuze that activates after impact.

M54 time and super-quick (TSQ) fuze: powder train burning fuze that can be set for time delay (slow burn) or super-quick (flash ignition) detonation on impact.

M77 time and super quick (TSQ) fuze: powder train burning fuze that can be set for time delay (slow burn) or super-quick (flash ignition) detonation on impact.

M78 concrete penetrating (CP) fuze: delay fuze that was set off after the shell had impacted and buried itself to increase the damage done.

M84 mechanical timing (MT) fuze: clockwork fuze that can be set from 0 to 25 seconds in 1-second intervals; seconds were indicated by vertical lines and 5-second intervals were indicated by metal bosses to allow it to be set in low-light or night-time conditions.

M84A1 mechanical timing (MT) fuze: clockwork fuze that can be set from 0 to 50 seconds in 2-second intervals.

Users

It may be found in nearly all the non-Communist countries, including:

Austria: used on M21 mortar motor carriage

Belgium: made under license

Republic of China

Colombia

Dominican Republic

El Salvador

Ethiopia

France

Greece

Guatemala

Haiti

Honduras

Japan

Laos

Libya

Mexico

Myanmar: M-43

South Korea: The Armed Forces was equipped with 386 M1s before the Korean War, and 822 were in service with the Army by the end of the war. Began replacing with M29A1 or KM29A1 in 1970s.

Turkey

Thailand

United States

Uruguay

South Vietnam

North Vietnam

Vietnam

 

US Army 81mm mortar crew in jungle. Position of mortar tube almost vertical indicates enemy is very close.

Original caption:  "Members of a Negro mortar company of the 92nd Division pass the ammunition and heave it over at the Germans in an almost endless stream near Massa, Italy. This company is credited with liquidating several machine gun nests..."  circa November 1944. (US National Archives     208-AA-47U-6)

Original caption:  "Getting across the Rhine wasn't all there was to it. There was the little matter of establishing a beachhead. We threw our mortars at them and everything else we had until they finally gave way." 1945. (US National Archives 208-YE-133)

Original caption: How 81mm mortar observers work, is demonstrated by SSGT Glenn K. Keller, left, and PFC Virgil Williams using binoculars and phone, near Oberwampach, Luxembourg. Both Men are with Co. D, 358th Inf. Regiment, 90th Infantry Division, January 25, 1945. (US National Archives 111-SC-330445)

Original caption: High up on a knoll commanding enemy positions on the island of Mindanao, P.I., the crew of an 81 mm mortar from one of the 162nd Infantry's Heavy Weapons Companies start to lay down mortar barrage in support of the troops of the 162nd Infantry, 41st Infantry Division advancing against Japanese in that area. (US National Archives 111-SCA-Album 2975 066)

Members of the 504th Parachute Infantry Regiment prepare to fire an 81mm mortar during the battle for Italy. September 1943.

81mm Mortar Carrier M4 of 41st Armored Infantry, 2nd Armored Division, in April 1944. The vehicle was modified so that the mortar will fire in forward direction. April 1, 1944.

 81mm mortar crew in action at Camp Carson, Colorado. April 24, 1943.

U.S. First Army soldier manning an M1 81mm mortar listens for fire direction on a field phone during the German Ardennes offensive. January 19, 1945.

M4 Mortar Carrier. March 25, 1942.

 81mm mortars support Patton's drive on Palermo.

 L-R: Pvt. Hubert Reiner, Pfc. Charles Strong and Cpl. Ken Shane. November 12, 1942. Tynan, Northern Ireland. 1st Battalion, 133rd Infantry Regiment, 34th Infantry Division.

Men fire smoke shells from an 81mm mortar supporting infantrymen of the U.S. First Army as they advance on a pillbox. 424th Infantry Regiment, 106th Infantry Division. February 28, 1945.

Front row, left to right: Pfc. Albert Bartolussi; S/Sgt. Louis Zompa; rear row, left to right: Armand Lesage Jr.; Cpl. Roger L. Leavitt; and Pfc. Leopold Freda. They are all fighting with the 306th Regiment, 77th Infantry Division. Okinawa. May 18, 1945.

Pvt. Ray E. Thiel of 3rd Bn., Mortar Platoon, 504th Parachute Infantry Regiment, 82nd Airborne Division, cleans 81mm mortar. Cisterna area, Italy. March 8, 1944.

The mortarmen of the 76th Division, Third U.S. Army, are firing their 81mm mortars into German positions across Rhine River. March 24, 1945. Company H, 2nd Battalion, 417th Infantry Regiment, 76th Infantry Division.

Firing a mission with 81mm mortar, L to R, Pvt. Ernest Dolloff and Cpl. John F. Richards, Company D, 141st Infantry Regiment, 36th Infantry Division. Haguenau Area, France. March 9, 1945.

Mortar crew sheltered behind the Maginot Line pillbox near Lembach, prepares to fire 81mm shells at enemy. 3rd Battalion, 157th Infantry Regiment, 45th Infantry Division. December 13, 1944.

Infantrymen fire 81mm mortar over house in Wingen. 180th Infantry Regiment, 45th Infantry Division. December 15, 1944.

Mortar team prepares to fire 81mm mortar shell to halt advance of enemy patrol in woods between American-held Ariendorf, and Germany-held Honningen. Company M, 394th Infantry Regiment, 99th Infantry Division.  March 14, 1945.

Men of the Mortar Platoon, 126th Inf. Regt., 32nd Div., are shown firing the 81mm mortar on the Japanese positions in the Orboredo River sector, Luzon, P.I. February 25, 1945.

Heavy 81mm mortar firing into Japanese positions across the Tsinamutu River, near Kuraio Mission, Bougainville. February 24, 1944.

M21 81mm Mortar Carrier at tests. April 28, 1944.

Lippisch P.11: German Tailless Tactical Fighter-bomber Project

Artist concept of the unbuilt Lippisch P.11 tailless tactical fighter-bomber project of December 1942 (not to be confused with the P.11/Delta VI fighter-bomber project of 1943-1944).

During 1942, while still working on the Messerschmitt Me 163 rocket fighter, Alexander Lippisch conceived a larger but similarly tailless bomber with twin jet engines buried in a thick wing, designated P.11.

Following his departure for his own independent design office near Vienna in Austria, Lippisch returned to the P.11 and radically revised it. The fuselage shrank to a short forward cockpit nacelle. The engines were placed quite close together inside the wing, with intakes in the roots and the otherwise straight trailing edge cut back for the exhausts. The wing planform was a cropped delta of moderate sweep. Small twin fins were located either side of the trailing edge cutback. Construction of a full-scale mock-up began in 1943. 

By the time work on an experimental prototype was begun, the project had become the Delta VI. Around this time Lippisch conceived of a "power wing", a hollow monocoque shell whose interior formed the internal duct of the main powerplant. He initially intended the Delta VI to have such a wing construction, but later drawings suggest that this was too difficult to realize under the prevailing war conditions.

On 16 and 24 June 1944 the USAF bombed Vienna, destroying the factory where prototype V1 was under construction and killing over forty of his co-workers. The prototype was moved to a new site but could not be completed before the Russian arrival in Vienna caused Lippisch and his colleagues to flee.

Lippisch went on to further develop the power wing concept in his P.12 and P.13a and b projects. 

Three-view drawing of the September 1942 version of the P.11.

Wind tunnel test model of the September 1942 version of the P.11.

Three-view drawing of the December 1942 version of the P.11.

Version P.11-121 was designed in May of 1943 in two versions.

Another version of the Version P.11-121 that was designed in May of 1943.

 The P.11-121 wind tunnel test model.

 Artist's sketch of the P.11-121.

Drawing of a P.11 in an attack dive.

Panzernest: German Small Machine Gun Bunker

A well camouflaged Panzernest.

In Italy the Germans had been using a mobile steel pillbox, nicknamed the "Armored Crab," which made its first appearance on the Russian front in 1943. These prefabricated bunkers, without rotation, had an armored casting carapace armed with a machine gun.

In the front of the pillbox, there was a small embrasure for the machine gun, with an observation peephole above. When necessary, these openings were covered outside by a heavy metal shield, which could be moved either to the right or left of the embrasure by means of a lever inside the pillbox. On top of the pillbox were two collapsible periscopes, also regulated from the interior. The entrance to the pillbox was a small door in the rear; this was locked from the inside by means of two brackets.

Under combat conditions the observer looked through one of the periscopes to observe and direct the gunner's fire. The gunner observed through the forward slit. Protection from the front against rifle, grenade and artillery fire was by means of the iron slit cover which was manipulated to cover or open the slit from the inside.

Inside the pillbox there was sufficient room for both members of the crew to sit comfortably and move around to a limited extent. There was a small heating stove and a ventilating apparatus, operated by a foot pedal, which provided sufficient changes of air when all the vents were closed. There was enough ammunition for 5 to 10 hours of fire.

Front of a Panzernest.

 

Rear of a Panzernest with a Soviet soldier in the hatch opening.

Rear view of a Panzernest with the hatch door open.

Panzernest ready for placement.

Front view of a Panzernest after being dug out with Soviet soldier standing guard.

Rear view of the same Panzernest.

Interior view of the Panzernest showing the mounting for a machine gun.

Another interior view of the machine gun mounting.

American soldier inside the cramped space of a Panzernest.

American soldier examining a Panzernest that had not yet been placed in position.

Two British soldiers inspect a Panzernest south of Rimini in Italy, September 27, 1944. (Imperial War Museum NA18995)

Another view of the same Panzernest seen a short time later; note the added sign pointing the way to the showers for a British unit. (Imperial War Museum NA19012)

British soldiers inspect a Panzernest in Italy, June 2, 1944. (Imperial War Museum NA15778)

Soviet soldiers examining a portable German Panzernest small machine gun bunker, referred to by the Red Army as the “Crab”.

Captured Panzernest being examined at a trophy exhibit in Moscow.

Four Panzernests being transported by rail to the front along with a Bergepanther.

Brand new Panzernest under a GI's inspection. Note the wagon-like wheels, in wood and metal.

A GI examines a Panzernest that was being transported to a position, with another in the background.

American M31 (T2) tank recovery vehicle moving a Panzernest that is hung from the vehicle’s crane; removed from the Gustav Line, Mt. Lungo, Italy, January 1944.

Illustrations of a Panzernest from a wartime intelligence bulletin.

Drawings of a Panzernest from a Russian intelligence bulletin.

Drawings of a Panzernest.

Drawings of a Panzernest from a Russian intelligence bulletin.

Panzernest cutaway: 1) Panzernest casting armor; 2) Periscopes; 3) Air vent tube; 4) Armored lip of the machine gun; 5)Machine gun mount; 6) Shelves (metal or wood); 7) Air filter; 8) Pedal for air fan.

Panzernest in transit (bottom) and before installation (top). The metal shell is carried upside-down and flipped into the trench.

Panzernest being towed by a  Opel Blitz 2.5-ton truck.

Panzernest sectional view.

Panzernest sectional view with machine gunner.

Why Join the Manhattan Project?

By some estimates, over 600,000 people worked on the Manhattan Project. Workers joined the project for very different reasons. The vast majority of the Manhattan Project workers were not aware of what it was trying to accomplish. It was only project officials and top scientists who were aware of the Manhattan Project’s true nature. Bill Wilcox, who worked at Oak Ridge, recalled that when he asked in his job interview what he would be working on, he was only told, “No, can’t tell you. Secret! Secret, secret, secret!” It is impossible to pinpoint all the determining factors for wanting to work on the Manhattan Project, but this article will spotlight some of the main reasons why so many people were willing to work on a top secret wartime project.

Link to article at the Atomic Heritage Foundation website