Single weapon that had the greatest effect.

Surprised no one has mentioned the GS Truck. Did one of the American Generals say it was the truck that one us the war.


Before anyone says it's not a weapon I bet it would kill you if it hit you

 

I'm going to go back to the simple portable radio. Best known is the SCR-300, which is that backpack style radio that had a voice range of up to 5 miles, but there were dozen other radio types available with similar capabilities. On the American side, almost all of these radios had multiple frequencies so that a platoon commander could call the tanks in his area on one channel, the artillery net on another, the company/battalion/regiment on yet another. if he couldn't reach one or the other because of range, then the messages would be passed through any intermediary. The artillery net in particular, was highly redundant and connected to other divisions and even other Corps.

Without the radios, you were stuck with wires. And even in non-battle conditions, those hastily laid wires were constantly being cut by vehicles or even livestock. In battle, your wire comms invariably went out as soon as the shooting started. Vehicles and armor moved in every direction cutting the wires, bullets and shells cut the wires, every soldier that crossed the line knew to cut every wire he saw.

In battle, on the American side (and the British also had a pretty good radio net), everybody from the squad level on up was on the same page. Division level artillery could be landing on the enemy within 3 minutes, called in by a squad leader. Mortars and the Cannon Company arty could be landing on the enemy in even less time than that. If there was a company of tanks near by, they could be rolling in minutes - talking directly to some Lt. down at the platoon level.

The Germans and Japanese did not have that flexibility. once the wires began failing, comms became a ponderous and time-consuming affair. When those Shermans came out of the woods, there was no way Lt. Fritz was going to get artillery directed on them or call in the panzers in time to do any good. If the company on either side was forced to withdraw, it might be a long time before everyone else knew they were being flanked. If he could finally call in artillery, the time delay might mean it was falling in a place where the enemy no longer was. If the panzers came, he couldn't tell them about the AT gun that just showed up here or there - and panzers that spotted it couldn't tell each other.

At the ground level, it isn't just the weapons it's the ability to employ those weapons at the right time and place. Good comms made that possible.

 

Just to add a bit to Kodiak Bears post, the Germans were terrified of the Piper L-4. They knew that when they saw one overhead, a rain of artillery would soon follow

 

Dave, the Germans were even afraid to shoot at those spotting planes, because as soon as their muzzle flashes were spotted a barrage would land on them. You'd think flying those slow little planes would be a very dangerous business, but in fact the losses were pretty low because of the consequences of shooting at one and missing.

 

And the casualty percantages in relation to the Numbers served:

UK and Crown Colonies (5,896,000) 6.6 %
India-(British Colony) (2,582,000) 3.4 %
Australia (993,000) 4.0 %
Canada (1,100,000) 4,1 %
New Zealand (295,000) 4.0 %
South Africa (250,000). 4,.8 %

To be fair they also helped a lot - but of course we would have hoped the official Sweden to do more...

 

In answer to the original question how about the British corvettes? They at the least prevented the Germans from winning the battle of the Atlantic and contributed greatly to the allied victory in that battle which allowed the movement of vast quantities of material from the US to the other allies and US forces to Europe. They also inspired the US DE design which proved so useful in both oceans. I was originally going to say the Liberty ship but I don't think they qualify as a "weapon system" which was stated in the OP.

 

My uncle Ed would say the A bomb......he fought his way through the ETO in the 79th Division and then slated to join the PTO when the bomb was dropped.

 

Submarines, especially in the Pacific; This weapon of war was credited with the destruction of the Japanese merchant and tanker fleet, thus strangling Japans economy as well as destroying a large portion of the IJN itself, and thanks to a Dutch sub in sinking a transport ship transporting equipment and refinery personnel headed to the DEI, delayed the repair of the oil refinery's there which had been thoroughly demolished by the British and Dutch, so by the time they were back up and running, the American submarine fleet was making mincemeat out of their tankers.

 

A second vote here for submarines...... somehow the German U-Boats get all the publicity, but the American submarine effort was positively devastating to Japan.

 

The M1 Garand.

 

Agreed!

 

I recall Eisenhower was asked this very same question and came up with a list of 4 decidedly unsexy items: the bulldozer, the jeep, the C47 cargo plane and the 2 1/2 ton truck.

 

I can't blame him. These were necessities that get overlooked. The men and women who were operating behind the scenes were crucial. The logistics of moving men and materiel from the ships, to the beaches, to the front line troops was massive. Allied production and improvisation was astounding.

 

after the a-bomb, the aircraft carrier.

 

another good call here.....the only thing is it dominated the Pacific, but not Europe

 

Well the jeep carriers made a significant impact in the Battle of the Atlantic and carriers also played an important part in the Med.

 

Has anyone mentioned Higgins boats used by most if not all of the Allies for the majority of amphibious landing operations in both theaters of the war?

 

Going to a different extreme. I nominate a pistol the Fabrique Nationale model 1910 semi-automatic pistol iwhat's more I'm nominating the specific one used on 28 June 1914. At least assuming the wiki page at that follows got the right weapon:
http://en.wikipedia.org/wiki/Assassination_of_Archduke_Franz_Ferdinand_of_Austria

 

I also say radios.

In the Great War the poor infantry-artillery communication was probably the biggest reason why the fronts remaind almost static. By the time artillery reacted to the attacking infantry's requests hours had passed and the situation of the infantry had already changed.

Oh and imagine naval, particularly carrier warfare w/o radios.

 

As well as armored warfare. One can argue that signals such as flag or lights can be used but radios did make things a lot easier and more convenient.