Were the enclosures of rural land responsible for the supply of workers to factories in the 18th and 19th century in England?
Most people in medieval England would have gotten their food from subsistence farming on land rented from a manor and payed for in labour, while during the Industrial revolution most people in England would have lived in cities. The question is if the enclosures was responsible for the supply of labour to factories.
The answer is no.
Enclosing land was a process that started already during the Tudors, as this system of paying in work and getting payed in land was growing increasingly inefficient. The Inclosures act of 1773 and later enclosure acts as such only helped speed up that process, which would have happened anyway.
But the enclosing itself did not create a surplus of labour for factories, because people would still have to eat, and the land still needed to be farmed. The enclosures only helped landlords reorganize the small strip farming system used into larger, more efficient fields.
The real change, and what created real surplus in labour was the increase in yield you got from the land, meaning that more people could be supported with the same amount of farming work. This does come partly from the enclosures, as the fields could be used more efficiently, but the big change comes from the inventions in farming that happened during the 18th century, spearheaded by such people as Jethro Tull, no sorry, I mean Jethro Tull.
That meant that all these other people could be fed without working on the farms, which meant that they were available for other work. This agricultural revolution is the primary cause of the work surplus that lays the ground for the industrial revolution.
Proof for this can be found in looking at how many people that lived on the country side. Between 1500 and 1850, the time of the enclosures, rural population approximately doubled. At the same time, the population living in cities went from approximately a couple of hundred thousand, to around 12-13 million. If the supply of labour came from people being forced from the land, the population in the country side would have decreased, not doubled.
No. As EP Thompson admirably demonstrates in Making of the English Working Class, the proletariat was already in existence in Britain and Ireland at the peak of the enclosures in a "pre-factory" system. As Engels and Marx demonstrate, and as reaffirmed in the Italian influenced Autonomist tradition, the purpose of the factory was to smash pre-existing forms of proletarian composition; from Thompson's work, the frame knitters and the London Mob.
The enclosures leading up to the factory system displaced a rural crofting population into agricultural labour, where they already competed with an Irish rural proletariat who had been displaced en masse by the most brutal forms of primary accumulation or enclosure known.
Enclosure relates to the destruction of the rural moral economy, the factory system to the destruction of the urban moral economy.
And Hammond and Hammond (1911) Village Labourer 159ff. Enclosure, in relation to wage labour, was about forcing agricultural wage labour, "[T]he large farmer wanted a permanent supply of labour which was absolutely at his command. Moreover, the roundsman system maintained his labourers for him when he did not want them.… The report of the Poor Law Commission in 1834 showed that these prejudices were as strong as ever. 'We can do little or nothing to prevent pauperism; the farmers will have it: they prefer that their labourers should be slaves.'"