As the wars progressed, the extremists obtained a dominant role within Parliament and in its military forces, to the point where, as a narrow clique at the centre of power, they were able to bring about the execution of a king and the abolition of the monarchy. How and why this came about is the subject of enormous academic debate. The course of events was complex and the different strands of opinion had varying degrees of influence at different times. War tends to produce polarisation between the opposing sides, especially where, as in 1642-43 and again in 1646-47, attempts to broker a peaceful settlement end in failure. A leading voice of moderation was silenced when John Pym died in December 1643, but divisions had already begun to show themselves within the Commons. Except for conservatives such as Denzil Holles who were prepared to accept peace at almost any price in order to avoid social disorder, Parliament accepted that the military defeat of the king was the essential preliminary to a constitutional settlement, but there was disagreement as to how this victory could be achieved, and the form which that settlement would take.