Spinola, then entering the territory of Cleve, took session of Orsoy, an important place on the Rhine, besides Duren, Duisburg, Kaster, Greevenbroek and Berchem. Leaving garrisons in these places, he razed the fortifications of Mulheim, much to the joy of the Archbishop and his faithful subjects of Cologne, then crossed the Rhine at Rheinberg, and swooped down upon Wesel. This flourishing and prosperous city had formerly belonged to the Duchy of Cleve. Placed at the junction of the Rhine and Lippe and commanding both rivers, it had become both powerful and Protestant, and had set itself up as a free Imperial city, recognising its dukes no longer as sovereigns, but only as protectors. So fervent was it in the practice of the Reformed religion that it was called the Rhenish Geneva, the cradle of German Calvinism. So important was its preservation considered to the cause of Protestantism that the States-General had urged its authorities to accept from them a garrison. They refused. Had they complied, the city would have been saved, because it was the rule in this extraordinary campaign that the belligerents made war not upon each other, nor in each others territory, but against neutrals and upon neutral soil. The Catholic forces under Spinola or his lieutenants, meeting occasionally and accidentally with the Protestants under Maurice or his generals, exchanged no cannon shots or buffets, but only acts of courtesy; falling away each before the other, and each ceding to the other with extreme politeness the possession of towns which one had preceded the other in besieging.
The citizens of Wesel were amazed at being attacked, considering themselves as Imperial burghers. They regretted too late that they had refused a garrison from Maurice, which would have prevented Spinola from assailing them. They had now nothing for it but to surrender, which they did within three days. The principal condition of the capitulation was that when Julich should be given up by the States Wesel should be restored to its former position. Spinola then took and garrisoned the city of Xanten, but went no further. Having weakened his army sufficiently by the garrisons taken from it for the cities captured by him, he declined to make any demonstration upon the neighbouring and important towns of Emmerich and Rees. The Catholic commander falling back, the Protestant moved forward. Maurice seized both Emmerich and Rees, and placed garrisons within them, besides occupying Goch, Kranenburg, Gennip, and various places in the County of Mark. This closed the amicable campaign.