The youngest of the seven sons of John Grubb and his wife Frances of Brandywine Hundred, Peter first learned the stonemasonry trade.
As he started to operate Hopewell, Peter soon located three mountains of magnetic iron ore just west of the furnace.
[5] They took over operation around 1765, after the lease expired, and quickly expanded the business, later becoming significant providers of munitions to the Revolutionary War effort.
But later generations, starting with Peter Jr.'s son Henry Bates Grubb, built on the remaining holdings with great success.
From 1840 to 1870 the Grubbs were among the leading iron manufacturers in Pennsylvania, with Mount Hope Estate serving as their center of operations.