among the nobility of these provinces to erect themselves into an independent republic, strengthened by a perpetual alliance with the United Provinces against the power of Spain.  But the plot failed, chiefly, it is said, by the imprudence of the king of England, who let the secret slip, from some motives vaguely hinted at, but never sufficiently explained.  After the death of Isabella, the prince of Brabancon was arrested.  The prince of Epinoi and the duke of Burnonville made their escape; and the duke of Arschot, who was arrested in Spain, was soon liberated, in consideration of some discoveries into the nature of the plot.  An armistice, published in 1634, threw this whole affair into complete oblivion.

The king of Spain appointed his brother Ferdinand, a cardinal and archbishop of Toledo, to the dignity of governor-general of the Netherlands.  He repaired to Germany at the head of seventeen thousand men, and bore his share in the victory of Nordlingen; after which he hastened to the Netherlands, and made his entry into Brussels in 1634.  Richelieu had hitherto only combated the house of Austria in these countries by negotiation and intrigue; but he now entered warmly into the proposals made by Holland for a treaty offensive and defensive between Louis XIII. and the republic.  By a treaty soon after concluded (February 8, 1635) the king of France engaged to invade the Belgian provinces with an army of thirty thousand men, in concert with a Dutch force of equal number.  It was agreed that if Belgium would consent to break from the Spanish yoke it was to be erected into a free state; if, on the contrary, it would not co-operate for its own freedom, France and Holland were to dismember, and to divide it equally.

The plan of these combined measures was soon acted on.  The French army took the field under the command of the marshals De Chatillon and De Breeze; and defeated the Spaniards in a bloody battle, near Avein, in the province of Luxemburg, on the 20th of May, 1635, with the loss of four thousand men.  The victors soon made a junction with the Prince of Orange; and the towns of Tirlemont, St. Trond, and some others, were quickly reduced.  The former of these places was taken by assault, and pillaged with circumstances of cruelty that recall the horrors of the early transactions of the war.  The Prince of Orange was forced to punish severely the authors of these offences.  The consequences of this event were highly injurious to the allies.  A spirit of fierce resistance was excited throughout the invaded provinces.  Louvain set the first example.  The citizens and students took arms for its defence; and the combined forces of France and Holland were repulsed, and forced by want of supplies to abandon the siege, and rapidly retreat.  The prince-cardinal, as Ferdinand was called, took advantage of this reverse to press the retiring French; recovered several towns; and gained all the advantages as well as glory of the campaign.  The remains of the French army, reduced by continual combats, and still more by sickness, finally embarked at Rotterdam, to return to France in the ensuing spring, a sad contrast to its brilliant appearance at the commencement of the campaign.