English employer advantage spawned a revolutionary confluence of English and Irish radicalism.

Evidence

E. P. Thompson, reviewing the observations that Engels had made on the positive (revolutionary) effects consequent to the mixture of the two “races” in the working class (“the more facile, excitable, fiery Irish temperament with the stable, reasoning, persevering English”), himself paused to reflect on the political possibilities that English capitalist production had inevitably produced: … It was an advantage to the employers, at a time when precision engineering coexisted with tunnelling by means of shovel and pick, to be able to call upon both types of labour. But the price which had to be paid was the confluence of sophisticated political Radicalism with a more primitive and excitable revolutionism. This confluence came in the Chartist movement… . Once before, in the 1790s … it seemed possible that English Jacobinism and Irish nationalism would engage in a common revolutionary strategy. If O’Connor had been able to carry Ireland with him as he carried the north of England, then the Chartist and “Young Ireland” movements might have come to a common insurrectionary flash-point. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 257

Categorization

• XREF: Directly addresses the reader’s question about the rise/height of the radical working-class tradition; the Chartist convergence is a candidate high point.
• DEEPTHINKING: Thompson’s counterfactual - that the very labor stratification employers imposed on ethnic lines could have fused into a unified revolutionary strategy - is a dense, paradigm-adjacent observation about how capital manufactures its own enemies.