The origin of the name “Lammers”.
North German and Dutch: patronymic from the personal name Lambert.
Important historical events defined East Frisia in the late 18th Century and the early beginnings of the 19th Century. The Prussians were in control from 1744 to 1801. Many of the cities and townships had to learn a new way of legal administration they had not known before; re. Allgemeines Landrecht (Prussian civil code). In 1801 East Frisia came under the control of France during the Napoleonic Wars. This lasted until 1806 when parts of East Frisia were split up under the French Empire of Holland. By 1810 East Frisia itself came under the rule of the now existing French Empire, Emperor Napoleon I.
In 1811, two major historical events were to occur.
The first was the introduction of Code civil des Français or known as the Napoleonic Code. This civil code, based on Roman law, brought about changes to the existing legal system and the administrations of cities and towns. "Mayors" now oversaw local administrations. They were not part of the old system of the Elders of the town based on social standing nor anything related to the Principality which was known in prior centuries.
Afterwards, this change brought about the second significant historical event during this period. All citizens were required to take on a surname. This was to rid the centuries-old Patronymic naming system of East Frisia. The reasoning behind this law was two-fold. This change would help to streamline the affairs of the legal system and city and town administrations. Secondly, a surname listing would provide ease in structuring the tax rolls. After all, Napoleon had to find ways to pay for his previous wars.
The Patronymics of the East Frisian naming culture was based on giving the children a derivative, affix or genitive usage of the Father's name (or Grandfather; e.g. a paternal ancestor).
From the above you can understand how, "Lamberts" has now become the surname “Lammers”.