During the 15th and 16th Centuries, the wars waged between France and Burgundy and later between France and Spain brought havoc and devastation throughout the Luxembourg region, and Orval was not spared. In this difficult context, the Emperor Charles-Quint showed his kindness in allowing a forge to be set up on the abbey's own land. In this same context of the early 16th Century should be placed the reconstruction of the nave of the church which was in danger of falling into ruin. The dedication of the church took place in 1533 and we know that in that year the community numbered 24 members.

While the 17th Century was to be one of disaster for the Low Countries, for Orval it was to be the highest point of its development. Two Abbots acquired a reputation throughout the whole Order. The first, Bernard de Montgaillard, from southern France, managed, despite the opposition of the community, to have himself appointed Abbot of Orval by Archduke Albert and Isabelle (1605). 'From that moment he devoted himself to his monks who finally became very attached to him. He put the monastery back on its feet economically and restored the buildings. But more especially he was a precursor in giving his community reform constitutions which led to an increase in fervour. Novices came in great numbers; in 1619 the community was composed of 43 members: 27 professed monks, 8 lay brothers and 8 novices.

Shortly after Bernard de Montgaillard, a new catastrophe hit Orval ; in August 1637 at the height of the Thirty Years War, the troops of the Maréchal de ChâtiIlon pillaged and completely gutted the monastery and its dependencies. The reconstruction took place in a climate of insecurity through to the end of the century.

From 1668 to 1707, Orval had another great Abbot at its head, Charles de Bentzeradt, a native of Echternach (Luxembourg). This austere monk was above all a reformer. Taking as model what Abbot de Rancé had accomplished at the Abbey of La Trappe in Normandy, Charles established the "Strict Observance" in his own monastery. He received numerous novices and so was able, in 1701, to found the Abbey of Düsselthal, near Düsseldorf, and to erect as Priory the house of Conques, on the river Semois. After his death, the monks of Orval sent reinforcements to the Abbey of Beaupre in Lorrain and reformed the monastery. In 1723 the community numbered 130 members and was "the most numerous of the Empire." Jansenism had, unfortunately, infiltrated the community and the crisis broke out in 1725. About fifteen of the monks preferred to leave the monastery; they were to set up, near Utrecht, the religious house of Rhijnwijk.

Material prosperity went hand in hand with religious fervour : the monks' agricultural and industrial domains continued to grow. From the end of the 17th to the middle of the 18th Centuries, the forges of Orval were the spearheads of the western steel industry.

From 1760 onwards, the revenues were mainly given over to the building of a new monastery for which the plans had been drawn by the famous architect Laurent-Benoit Dewez. The new church was consecrated in 1782 ; after that the work slowed down and then stopped for want of funds

In 1789 the French Revolution broke out and all the possessions of Orval across the border were immediately confiscated. The abbey lived through various alerts, more or less serious, until the decisive day, 23rd June 1793, when the revolutionary troops led by General Loison sacked and burned the monastery Everything was wiped out. The community withdrew to its refuge in Luxembourg and then to the Priory of Conques. The community was officially suppressed on the 7th November 1795 and its members disbanded. For more than a century the charred walls of Orval were at the mercy of the weather and of stone- and treasure-seekers.

Ruins