Sure, it's playable against the triangle formation by black, but a lot of things are, because it's a passive setup. For instance, you could go 4.e4 instead, with an interesting game.
The pawn on c3 is meant to support the center - since black doesn't not attempt to challenge white's dark squares in the center at all, the pawn is better on c4.
I'm not an expert on d4-d5 structures, since I rarely see them in my games due to my openings, but this should be absolutely fine in this variation.
I hate the Stone Wall but I think it is always playable if Black's pawn is on d5.
Wait, your pawn is on c4. Abort, abort, ITS A TRAP.
There is a flaw in your logic, and this is a very unimproved Stonewall! By playing c4, you have removed an important "stone" from the wall. Even though Black has already played c6, after the mistaken 5.f4. Black can play 5...c5 with at least an equal game. The whole logic of the Stonewall is that you build a passive, but unassailable center, You undermine that whole concept with an early c4
Well, this idea has been tested. In the Chessbase online database, the position after 1.d4 d5 2.c4 c6 3.Nc3 e6 4.e3 Nf3 has been reached in tournament play around 22,000 times. And the move 5.f4 has been chosen in exactly 7 of those games! A pretty emphatic rejection! And when white did choose 5.f4, he scored a sad 36%
c3 - not c4 and be true to history:
As the Rebel Army collapsed into retreat at the First Battle of Manassas [1861, American Civil War] General Bee tried to reorganize his fleeing troops. Looking at the hilltop he saw the one Rebel unit holding its position: the Virginia Infantry/Artillery Brigade of General Thomas J. Jackson.
"Rally round the Virginians," Bee called to his troops, "There stands Jackson like a stone wall!"
Before the day was over, the Rebels won the battle.
From that day forward, as he reeled off one ingenious campaign after another, he was no longer, "Thomas." He was Stonewall Jackson!
Now, to play the Stonewall, you have to play in the spirit of one of the scruffiest and religious-fanatic generals in history:
1. Even though some of his bloodiest battles were fought on Sunday, he would not risk sending a letter through the mail that might not be delivered by Sunday: a religious day of rest.
2. He would not eat pepper: he claimed it made his left leg ache.
3. He rode into battle with one arm raised, "to keep the balance."
4. His men called him "Ol' Blue Light" because his eyes seemed to glow during battle.
5. When a wounded reporter heard Stonewall himself was riding past the hospital camp he was in, he asked some soldiers to hold him standing up so he could see the great man. When he saw the scruffy, plain uniform Stonewall ride by, he was so disappointed he called out, "Oh, lay me down." For the rest of his life, Confederate troops would call out, "Lay me down," whenever Jackson passed by.
So, you are not allowed to consume pepper while playing the Stonewall and you can't play it in a 3 day/move game if the opponent might not respond before Sunday. While you move a piece by mouse or hand, the other hand mus be raised in the air. You must also try to make your eyes glow. Finally, you have to dress like a homeless person!
Sure, it's playable against the triangle formation by black, but a lot of things are, because it's a passive setup. For instance, you could go 4.e4 instead, with an interesting game.
The pawn on c3 is meant to support the center - since black doesn't not attempt to challenge white's dark squares in the center at all, the pawn is better on c4.
I'm not an expert on d4-d5 structures, since I rarely see them in my games due to my openings, but this should be absolutely fine in this variation.
I kind of disagree. I feel there is a reason why this opening is very unpopular, and it's that even though black's position seems outwardly passive, black always will end up taking on c4 and playing c5 (or otherwise e5, but that's not possible here). And when this happens the center can break and white's f4 move will not help him at all. Might even be a loss of time or a weakening move.
This is why in the Stonewall white should always keep the pawn on c3 so that if black does play c5-cxd4 white just maintains the structure and simultaneously black will only be able to exchange one pair of pawns instead of two (dxc4 and c5-cxd4) in the center.
OK cool, I learned something. I said it was fine because it didn't look that bad or anything. Although I would never play the stonewall as an opening.
Thanks MickinMD - that was fascinating stuff about Stonewall Jackson. I remember when I was about eight years old I won a prize at school for learning and reciting 'Barbara Frietchie', about when SJ's 'nobler nature within him stirred'. Funny to think of a short-trousered little boy in Leeds (Northern England) squeakily reciting about the American Civil War!
An interesting sideline