Nicolas, or rather, Colard de Mailly, Lord of Blangy-sur-Somme and of Conty, belonged to the party of the Duke of Burgundy.

Captain of Saint-Riquier, which had just been surrendered by the Lord of Offémont, (1422) he received from the English king, in 1423, on the recommendation of the Duke of Bedford, the seigneurie of Rambures, seized by d'Harcourt's men; then after the siege of Guise (1424) he received likewise the lands of Jean de Coucy.
In January 1426, Colard de Mailly was created Bailly of Vermandois.

That same year he took part in the siege of Mortagne in the retinue of the Earl of Salisbury and later in the Argonne campaign. On July 10, 1428, he wrote to the inhabitants of Reims to urge their obedience to the Burgundians. Colard never changed, as has been written of him, to loyalty to the King of France.

He retired to Chauny, in the fortress of Charles d'Orléans, from which, in 1431, the inhabitants routed him.
We find later mention of him as ambassador of the King of England at the Council of Arras; in 1441 he was among Jean de Luxembourg's men at the siege of Pontoise.

He died about 1457.