The Renault FT-13 (RAR!)

[Zor]

In this scenario Louis Renault in 1910 to 1912 designs an unusual vehicle ahead of shedule and pitches it to the french army, it looks like this...


The French army is impressed and in late 1913 it is adopted. By the onset of the great war, the french army has some 150 FT tanks in its fleet, with orders for more going up afterwards. Only the French military has tanks as of the outbreak of the war or has considered the idea valid.

What happens?

Zor

[Darmalus]

From what I heard, WW1 designs were too thin skinned to stop most hand held rifles. If true, then tank technology gets takes a step backward as everyone watches those expensive FTs get slaughtered by standard infantry and machine guns.

[Esquire]

Wikipedia gives the armor on the FT as 8-22mm, which - assuming that the 22mm is on the front face and decent-quality armor plate - should keep out .50 cal AP rounds at 200 meters. Hand weapons will not be an issue. Antitank rifles will, and artillery will obviously smash light tanks, but for the first couple weeks/months France should be able to use them fairly securely.

[Sea Skimmer]

Duh...yeah they can stop rifle bullets. Concentrated fire with rifle caliber machine guns could stop some tanks when firing AP bullets because it heated up the armor enough to start spalling it, but this was not a very reliable tactic on thicker armor, the thin turret of the FT-17 was highly vulnerable to it. Thus the development of heavy machine guns, leading to among other things the M1921 Browning .50cal which is somehow still being produced. On the other hand no WW1 tank could stop even the smallest caliber of solid shot from a cannon, the Germans even began converting obsolete 57mm blackpowder guns from the 1880s into anti tank pieces and found them effective. All WW1 tanks were also somewhat vulnerable to artillery fragmentation, but not shrapnel balls.

As for the actual effect of these tanks, the Germans most likely would have done what they did in real life, issue AP machine gun bullets. 1913 field artillery was still training for direct fire, this tactic actually had to be relearned from 1916 onward for effective anti tank fire. I'm not sure 150 tanks is going to be enough to make a signficant difference, simply because while they cannot easily be stopped by enemy fire, they have very little mobility in operational terms. They need to move by rail to the battlefield as tank transporting trucks don't yet exist, and the French would throw all the tanks into attacking Alsace Lorraine where they will breakdown and ditch themselves like crazy in the forests. The FT-17 had better speed and range then most WW1 tanks, but directly at the cost of having very poor cross country performance. Nobody could make engines powerful enough to get good all around performance out of the same vehicle in this timeframe, and of course nobody had sprung suspension at all.

The idea of holding the tanks back as a decisive reserve and thus leaving them available to fight near Paris is well, unlikely to have taken hold. If the French hadn't thrown everyone at Alsace Lorraine in the first place the WW1 deadlock most likely wouldn't have occured.

[LaCroix]

The FT usually had max. 16mm armor, only the Berliet-produced turrets had 22 mm. It also was badly constructed in respect to COG - most weight was front, so they fell into ditches and couldn't get out, or dug into mud. They installed a leverage platform at the back of the tank so you could balance it by adding weight, but this made that thing slower, of course.

There were transporting trucks for them, the Renault FU.

Anyway, 150 are not quite a lot. Especially since they are not quite suited for a mobile war, Poland-Sowjet conflict in 1920 showed that. The only thing they would be good for is to break through a trench line, and for that, you'd need more than that. (5-600, at least)

So, if they held them back until the 'race to the ocean' stopped and then used them as battering rams to puncture the line and push the Germans back, it would probably allow them to push the front line back into Benelux territory before the Germans come up with Panzerbüchsen and other suitable defences.

[Esquire]

That's worth something, particularly if "you cannot break trench lines without armor" worms its way into the French commanders' collective subconscious. France might be in a better position after the war if less of its men die pointlessly - they, with Britain and the US, will still win, obviously.

[Simon_Jester]

The problem is, again, that they're likely to be committed to the massive attaque à outrance into Alsace-Lorraine. So the initial wave of tanks gets bogged down in the field or dies when Crown Prince Wilhelm's 5th Army manages to get field guns into position to blow them away.

However, having a production line for light armor that will keep operating is going to help a lot. The Germans will develop antitank weapons, but the very existence of armor makes it a lot harder to build impenetrable trench lines, even if the tanks themselves are still individually vulnerable.

In the long run this will probably make the Western Front less of a complete deadlock, I think, though it would still be very ugly.

[LaCroix]

If you mean the August 21–23, 1914 action, then the initial wave of tanks will shortly get left far behind the infantry. These things move at a snail's pace overland - 8km/h under best condition and full throttle. Usually, it was half that.

Apart from the fact that the whole offensive (during foggy weather) ran into dug in Germans and well-placed artillery giving close support, the problem that your tanks are making you even easier to spot due to engine noise would make that operation even more of a failure than it originally was. The German artillery practically obliterated any unit caught in the open that day, and everything that could run de-assed the area pretty quickly. The tanks would have been caught in that chaos and are not mobile enough to avoid being overrun.