In 1550 he managed the move of the Reguliers, monks from the monastery in Stein, South Holland to a Double monastery in Gouda. The former home of the reguliers in Land van Steyn,, had been lost in a fire in 1549. The convent they moved to in Gouda, was renovated for them by order of George van Egmond and the former sacristy was remodeled into a choir which housed eleven stained glass windows. Despite these renovations, the Regulierskerk did not survive long after that, because the monastery reverted to the state after the Protestant Reformation in 1580 and the church was torn down. For centuries the Catholic Hofje, which was founded on the grounds of the monastery in 1563, was allowed to remain on the Raam in Gouda, but this too was finally torn down in 1958. In 1580, before destroying the Regulierschurch, the expensive stained glass windows and the accompanying cartoons were moved to the Janskerk, where they were most recently restored in 1922 and given a separate chapel.
Diocese Haarlem
In 1559 a new diocese was introduced, the diocese Haarlem, and Nicolaas van Nieuwland became bishop of this new diocese on November 6, 1561. He entered the city on February 1, 1562 with a formal procession. Van Nieuwland also became abbot of Egmond Abbey at the same time. At the time that Van Nieuwland was in Haarlem, the Protestant Reformation was gaining ground in the Northern Netherlands, and Haarlem was a seat of unrest due to the school there under the leadership of Dirck Volckertszoon Coornhert. Van Nieuwland was faced with a slowly shrinking Catholic population as the townspeople reverted to Protestantism and followed Coornhert, who sided with Lamoral, Count of Egmont and William the Silent, against the Catholic leaders of Van Nieuwland, the newly appointed Frederik V Schenck van Toutenburg, who received his orders from Philip II of Spain. Van Nieuwland's protector George van Egmond had died in 1559. Perhaps because of these developments, he became an alcoholic, and is registered as walking in processions drunk, earning him the local nickname Dronken Klaasje. He was asked to step down in 1569, and he was replaced by Godfried van Mierlo. Van Nieuwland returned to Utrecht, where he later died.
