I was inspired to seek this out after watching Jonathan Meades' duo of programmes, Magnetic North, in which he perambulated from Flanders to Finland along the North Sea and Baltic coasts.
The book, originally published in 1889, is a straightforward and interesting narrative of the history of the Hanseatic League. Although somewhat vague regarding its origins, it describes in its early chapters the state of affairs in north German towns during the period of Frederick Barbarossa, and the trading alliances that began to emerge at this time. It's interesting to note the specifically mercantile nature of the league, which frequently engaged (often, though not always, through the use of mercenaries) in piracy against its enemies, and whose business model was very much based on exclusive and monopolistic trading agreements. Zimmern describes various outposts of the league, especially in London, Norway, and Novgorod. Like many imperial adventures, there is a claim to have exercised a civilising influence, though that must be a view taken with hindsight, and also with a certain amount of salt; the primary motivation was always financial. It's interesting that the League had no support from, and indeed was generally regarded as illegal by, the Holy Roman Emperors under whose jurisdication it broadly fell. Zimmern compares the League with the city states of Italy in the same period, in which she asserts there was more enlightening intellectual activity as well as trade.
It's amusing to note that Meades highlighted herring and beer as distinctly Northern fare, and indeed herring played some role in the downfall of the Hansa, as the Reformation led to a decline in observance of Catholic fasting days. Zimmern chronicles further disarray during and after the Thirty Years War, though certain trading privileges existed, especially for Hamburg, into the nineteenth century.
Although the book was written without any twentieth century perspective, it is quite striking that much of its comment is relevant today. The book claims that the English word "sterling" is derived from the term "easterling", referring to Hanseatic money, the single currency of its day. The fourteenth-century version of the EDL, led by one Wat Tyler, apparently persecuted any merchant who could not pronounce "bread and cheese" without a foreign accent. The Hansa were the non-doms of their day, making substantial profits from trade but paying no taxes on it.