Scheduled to last only until 29 September, the truce was short-term; as of February Edward III ordered preparations for embarkation of military forces from Portsmouth. At this point the French king, Philippe VI, put an end to the truce by executing without trial (and despite prior agreements) Olivier IV de Clisson in Paris on 2 August, and then on 29 November a further fourteen Breton lords; Geoffroi de Malestroit, Jean de Montauban, Alain de Quédillac, Denis du Plessis, Guillaume II des Brieux and his brothers Jean and Olivier, and others. These were all supporters of Jean of Montfort. Even so, hostilities did not officially recommence till 1345; they were however pursued till 1362.
Sources
Georges Bordonove, Les Rois qui ont fait la France - Les Valois - Charles V le Sage, tome 1, éditions Pygmalion, 1988.
Arthur de La BorderieHistoire de la Bretagne réédition Joseph Floch Mayenne (1975), Tome troisième «Rupture de la trêve de Malestroit» p. 481-487.