[3] Quaker missionary work in the lower and middle Rhine River valley during the 1660s resulted in the conversion of a number of Mennonites in and around Krefeld.
In 1679 five of them, including Derick's brother Herman op den Graeff, were forcibly exiled from Krefeld.
[3] They were eventually allowed to return through pressure from the English Quakers, but by this time William Penn's Colony was being established (1681-1682).
[7] The opportunity to follow their Quaker beliefs without fear of persecution was undoubtedly a major factor in their decision to emigrate from Krefeld.
[13] His grandson John William (Johan Wilhelm) op den Graeff (1732 - between 1800 and 1804) immigrated in 1753 to Pennsylvania as well.
The 13 families from Krefeld had heard about the slave trade in the American colonies for the first time in Rotterdam on their trip to Pennsylvania.
[3] In 1691, Thomas Lloyd, Deputy General of Pennsylvania had granted a naturalisation to sixtytwo of the first Germantown settlers as citizens of Pennsylvania (and therefore of England) with the status of a freeman including the three Op den Graeff brothers and also other important members of the settlement, Pastorius and William Rittenhouse.
[17] The Krefeld Quaker advocates were the brothers Abraham and Herman op den Graeff who sided Keith.
[19] Derick or his brother Abraham is briefly mentioned in John Greenleaf Whittier's abolitionist poem "The Pennsylvania Pilgrim", published in 1872.
Teased the low backlog with his shodden staff, till the red embers broke into a laugh and dance of flame, as if they fain would cheer.