Thought this might be the song. It's by Phil Ochs.

Come you ranks of labour, come you union core,
And see if you remember the struggles of before,
When you were standing helpless on the outside of the door,
And you started building links on the chain, on the chain.
You started building links on the chain.

When the police on the horses were waitin' on demand,
Ridin' through the strike with the pistols in their hands,
Swingin' at the skulls of many a union man.
As you built one more link on the chain, on the chain.
As you built one more link on the chain.

Then the army of the fascists tried to put you on the run,
But the army of the union, they did what could be done.
Oh the power of the factory was greater than the gun,
As you built one more link on the chain, on the chain.
As you built one more link on the chain.

And then in 1954, decisions finally made,
The black man was a-risin' fast and racin' from the shade,
And your union took no stand and your union was betrayed,
As you lost yourself a link on the chain, on the chain.
As you lost yourself a link on the chain.

And then there came the boycotts and then the freedom rides,
And forgetting what you stood for, you tried to block the tide,
Oh the automation bosses were laughin' on the side,
As they watched you lose your link on the chain, on the chain.
As they watched you lose your link on the chain.

And the same man telling you that they'll take your jobs away,
He's the same man who was scabbing hard, just the other day,
And your union's not a union 'till he's thrown out of the way,
And he's chokin' on your link on the chain, on the chain.
And he's chokin' on your link on the chain.

And now the times are telling you, the times are movin' on,
And you're fighting for the same things, the jobs that will be gone,
Well it's only fair to ask you boys: Which side are you on?,
As you're building all your links on the chain, on the chain,
As you're building all your links on the chain.

Roger in Baltimore