An anti-tank grenade is a specialized explosive device to defeat heavily armored targets.
The first anti-tank grenades were improvised devices. The Germans were the first during World War One to come up with an improvised anti-tank grenade, taking their stick ("potato masher") grenade and taping two to three more of the explosive heads without the sticks to create one complete grenade. In combat, after arming, the grenade was thrown on top of the slowly advancing tank where the armor was thin.
During World War Two, various nations made improvised antitank grenades by putting a number of defensive high explosive grenades into a sandbag. Due to their weight, these were normally thrown from very close range or directly placed in vulnerable spots onto an enemy vehicle. Another method used by the British Home Guard in 1940 was to place dynamite or some other high explosive in a thick sock and cover the lower part with axle grease and then place the grease covered part in a suitable size tin can. The antitank sock was pulled out, the fuse lit and the sock thrown against the side of the tank turret in the hope it would stick until the explosion. If successful, it caused internal spalling of the armor plate, killing or injuring the tank crew inside. It is not known if this type of improvised anti-tank grenade was ever successfully employed in combat. By late 1940, the British had brought into production a purpose-built adhesive anti-tank grenade - known as the "Sticky bomb." 
When tanks overran entrenchments, hand grenades could be, and were, used by infantry as improvised anti-tank mines by placing or throwing them in the path of a tank in the hope of disabling a track. While this method was used in desperation, it usually proved more dangerous to the soldier on the ground than to the crew of the tank.
Purpose-designed anti-tank grenades generally use the shaped charge principle to penetrate tank armor, although the squash head concept is also used. In military terminology, warheads employing shape charges are called high explosive anti-tank (HEAT) warheads. Because of the way shaped charges function, the grenade must hit the vehicle at an exact right angle for the effect to work most efficiently. The grenade facilitates this by deploying a small drogue parachute or fabric streamers after being thrown.
Britain put the first anti-tank grenade into the field during the Second World War in late 1940 with the No 68 AT Grenade, which was one of the first "any" type anti-tank weapons of the shape charge or HEAT type. The No 68 was fired from a rifle using the Mills grenade cup launcher. The Type 68 had a penetration of 50 mm of armor plating, which was astonishing for 1940. Also developed by the UK during the war was the No 74 ST Grenade, popularly known as the "sticky bomb", in which the main charge was held in a glass sphere covered in adhesive. In anticipation of a German invasion, the British Army asked for ideas for a simple, easy to use, ready for production and cheap close-in antitank weapon. The ST Grenade was a government sponsored initiative, by MIR(c), a group tasked with developing weapons for use in German and Italian occupied territory, and they placed the ST Grenade into mass production at Churchill's insistence, but seeing how it was operated, the British Army rejected it for the Home Guard much less their regular forces.
The No 74 Grenade was later issued to troops as an emergency stop-gap measure against Italian tanks in North Africa, where it proved—to the surprise of many—highly effective. Later in the war, French partisans used the No 74 effectively in sabotage work against German installations.
Shortly after the German invasion of Russia in 1941, the Germans introduced the Panzerwurfmine(L), an extremely lethal close-quarter HEAT anti-tank grenade that could destroy the heaviest armored tanks in the war. The grenade was tossed overhand to land atop the tank. After release by the thrower, three spring-out canvas fins stabilized it during its short flight. The Panzerwurfmine(L) was lethal, and inexpensive to manufacture, but required considerable skill to throw accurately and was issued only to specially trained infantry tank-killer teams.
It did not take long after the Russians captured the German Panzerwurfmine(L) to come out with their own hand-thrown anti-tank grenade with a HEAT warhead. In 1940, they developed a crude antitank grenade that used the simple blast effect of a large high explosive charge, designated RPG-40, which was stabilized in flight by a ribbon released after it was thrown. The RPG-43 (developed in late 1943) was a modified RPG-40 with a cone liner and a large number of fabric ribbons for flight stabilization after release. In the last year of the war, they introduced the RPG-6, a total redesign of the RPG-43 with an improved kite-tail drogue in the handle and a standoff for the HEAT warhead, drastically increasing both accuracy and penetration, which was reported to be over 100 mm, more than adequate to cause catastrophic damage to any tank if it impacted the top. The Russian RPG-43 and RPG-6 were far simpler to use in combat than the German Panzerwurfmine(L)and did not require extensive training.
After the end of World War Two, many eastern European nations engineered their own versions of the RPG-6, such as the East German AZ-58-K-100. These were manufactured in the tens of thousands and given to 'armies of national liberation', seeing combat worldwide, including with the Egyptian Army during 1967 and 1973.
The first Japanese antitank grenade was a hand-thrown grenade, which had a simple 100 mm diameter cone HEAT warhead with a simple "all the way" fuse system in the base. (If dropped accidentally with the pin removed, it would explode). It had what looked like the end of a mop head on the tail end of the warhead. A soldier would remove the antitank grenade from its sack, pull the pin, and throw it gripping the mop-head as the handle. This was dangerous, as there was no arming safety after release and the thrower could strike something in his back swing before release. Penetration was reported only around 50mm.
The second Japanese antitank grenade—a suicide weapon—was nicknamed the 'lunge mine'. This weapon was a very large HEAT warhead on a five-foot stick. The soldier rammed it forward into the tank or other target, which broke a sheer wire that allowed a strike pin to impact a primer and detonate the large HEAT warhead—destroying both soldier and target. While crude, the Japanese lunge mine had six inches (150mm) of penetration, the greatest penetration of any antitank grenades of World War Two.
The U.S. Army first encountered the hand-thrown anti-tank grenade in 1944, in the Philippines (some believe they were locally manufactured). The later suicide 'lunge mine' first appeared in the U.S. invasion of Saipan and subsequent invasion of Okinawa. Tens of thousands of these crude devices were produced and issued to both regular units and home-guard units on the home islands of Japan before the war ended.
|US Army Early 1980s HAG Concept|
|Details of HAG concept (US Army)|
|Details of Combat Use of HAG (US Army)|
In the late 1970s, the U.S. Army was worried about the lack of emergency antitank weapons for issue to its rear area units, to counter isolated enemy armored vehicles infiltrating or being air dropped. When the US Army asked for ideas, engineers at U.S. Army laboratories suggested the reverse-engineered and additional safety improvements of the East German AZ-58-K-100 HEAT antitank grenade that had been obtained from various classified sources. This concept was called "HAG" for High-explosive Antiarmor Grenade. While the civilian engineers working for the US Army thought it was a great idea, it was rejected out of hand by almost all senior US Army officers with field experience, who thought it would be more dangerous to the troops who used them than the enemy. The idea was quietly shelved by 1985. This decision left many rear-area U.S. units with no heavier "antitank weapon" than the M2 heavy machine gun.
The most widely distributed anti-tank grenades today are the post World War Two Russian designs of the 1950s and 1960s, mainly the RKG-3.
Due to improvements in modern tank armor, anti-tank hand grenades are generally considered obsolete. However, in the recent Iraq War, the RKG-3 anti-tank hand grenade has made a reappearance with Iraqi insurgents who used them primarily against U.S. Humvees, Strykers and MRAPs, which lack the heavier armor of tanks. This has in turn led the U.S. to adopt countermeasures such as modifications to MRAP and Stryker vehicles by the fitting of "slate" armor or "bird cage" armor, which causes the antitank grenade to detonate too early.
- A 1941 issue of LIFE magazine showed a series of photo on how to make such antitank grenades along with X shaped slit trenches to protect the grenade thrower
- Ian Hogg "Grenades & Mortars" page 38 Ballantine Books 1974
- Ian Hogg "Grenades & Mortars" page 39 Ballantine Books 1974
- Chris Bishop "Weapons of World War II" page 207-208 Barnes and Nobles Books 1998
- Denis H.R. Archer "Jane's Infantry Weapons" page 462
- Chris Bishop "Weapons of World War II" page 214 Barnes and Nobles Books 1998
- Denis H.R. Archer "Jane's Infantry Weapons" page 464-465
- Note - see the External Images on the HAG in the "Anti-tank" section of this article for a detail drawings and how Russian anti-tank grenades operate
- edited by W.H. Tantum and E.J. Hoffschmidt "Second World War COMBAT WEAPONS - JAPANESE" page 174 and 184
- Eric C. Ludvigsen "Association of the United States Army GREEN BOOK 1984-85" page 348
- Schogol, Jeff (October 20, 2009) "MRAPs modified to deflect RKG-3 anti-tank grenades". Stars and Stripes (newspaper)