The “cog”, the vessel in the arms of Amsterdam, is a very well known mediæval type, of which the importance becomes marked in Western and Central Europe from and after the XIIIth century, when the Hanse towns and the Frisians improved it greatly.
This ship, which was very broad for its length, was hard to board, whence its usefulness in time of war.
The “cog” seems to date back further than the institution of the Hanseatic league (1250) judging by the fact that its name was known well before this date. Thus, the inhabitants of the Netherlands had to equip several cogs wherewith to fight the invasions of the Norsemen (810-1010). It was the application of the feudal system to navigation. (See LA CROIX, p. 88.) It is known that this policy was finally established under Charlemagne who subjugated the Frisians in 785 and the Saxons in 804. (Mr. J. C. DE JONGE, History of the Navy of the Netherlands, Vol. 1, p. 6.)
It is needless to say that everything was soon put to work to escape it. A charter of the Roman King Otho I (936-973) calls for a tenth of a “cog” (Kogschult) of which the product came to the bishop of Utrecht. It was the commutation for the obligation to serve the prince with cogs. This obligation seems, in principle, to have struck more especially the countries lying along the present Zuyder Zee. (Mr. DE JONGE, Vol. I, p. 7.)
The “cog” only appears for the first time in Germany in 1211, when the Emperor Otho IV allowed the inhabitants of Wismar to maintain two “cogs” (Cogken), and as many small vessels as they desired.
There are some who claim that the word cog, “Kuggr” in old Norse, comes from the Italian “cocca”, the Spanish “coca” or the old French “coche” and, consequently, they believe that the word is of Romance origin. This does not seem likely; the “cog” is a type of vessel copied from the old Viking boat and adapted to the special conditions of the navigable highways in the low lands of the North-West of Europe. Hence it was robust and full to facilitate grounding.
In reality, the “cog” was unknown in the Mediterranean; this follows from what the Florentine historian Villani relates in connection with the battle of Zierikzee. If this vessel had been a Mediterranean type, the author would not have directed especial attention to this form of ship. Hence the “cog” really belongs to Northern Europe and owes its perfecting to the Frisians and most of all to the Flemings.
The “cog” was generally in use in the XIIIth century and it may be assumed that the Norsemen already knew it in the time of the Vikings. Unfortunately, very little concerning it has come down to us. The oldest reproductions which we possess are those of the seals of Amsterdam and Harderwijk. But the ship which figures in the arms of the former city has undergone many changes in the course of the ages. Witsen says that it is an ill drawn figure and he imputes this defective work to the ignorance of the engravers. (WITSEN, p. 363.)