The motivations for the popular rebellion are complex.

Among them is a desire to reverse the plantations; rebels in Ulster are reported as saying, 'the land was theirs and lost by their fathers.'

Another motivating factor is a sharp antagonism towards the English language and culture that has been imposed on the country.

For example, rebels in county Cavan forbid the use of the English language and decree that the original Irish language place names should replace English ones.

A third factor is religious antagonism.

The rebels consciously identify themselves as Catholics and justified the rising as a defensive measure against the Protestant threat to 'extirpate the Catholic religion'.

Rebels in county Cavan state, "we rise for our religion. They hang our priests in England".

Historian Brian MacCuarta writes, "Longstanding animosities against the [Protestant] clergy were based on the imposition of the state church since its inception thirty years previously. Ulster Irish ferocity against everything Protestant were fueled by the wealth of the church in Ulster, exceptional in contemporary Ireland".

There are also cases of purely religious violence, where native Irish Protestants are attacked and Catholic settlers join the rebellion.

There are by early 1642 four main concentrations of rebel forces; in Ulster under Phelim O'Neill, ...