Wikipedia states that Bock Beer originally comes from Einbeck, Germany:
Bock is a type of strong lager beer, first brewed in the 14th century in the Hanseatic town of Einbeck, Germany, from which it gets its name (originally “Einbeck” / “Einbock”).
Wikipedia will probably get a failing grade in history on this subject. While Einbeck did have a brewing tradition that goes back a ways, the beer that we recognize today as ‘Bock’ would have been unrecognizable back then. For one, bocks are lagers, and lagering was more a process found in the Alpine region, rather than in the Saxony region back in the 1300′s. Second, the malts used in today’s bocks are more Bavarian based. This seems to me that the history of this beer is likely (although I may be wrong) to be Bavarian based.
A more likely history seems to be found here. Bock beer is the Bavarian attempt to recreate beer from Einbeck, rather than being from Einbeck. As Ray Daniels explains:
Although the Munich copy of the Einbeck beer bore little resemblance to the original, the resulting beer was still named after the city that inspired it. In the Bavarian dialect, it was called “Ainpoeckish Pier.” The beer was enjoyed by the citizens of Munich and soon replaced the original. Not long after, brewing ceased in Einbeck as a result of the Thirty Years’ War (1618-1648) and the name of the Munich-produced beer no doubt began to drift from “Ainpoeckish” to simply “Poeck” and ultimately to the “Bock” we know today.
But, as Daniels also notes, there are as many stories revolving around the creation of Bock beer as there are beer drinkers in Munich. So, what truly happened may be yet to have been uncovered.
What we do know is that Bock beer is traditionally brewed in the fall, concurrent with the harvesting of the fall barley crop. It is allowed to lager most of the winter, and becomes available for drink around March-April, depending upon the whim of the brewer.
When you think Bock beer, think malt, malt, malt. It is not a beer for hopheads. Because of the amount of malt used, the resulting wort ends up with a fair bit of more sugars than other beers, resulting in a higher alcohol content after fermentation. So if malt is the first characteristic of bock beer, a higher alcoholic content would be the second.
Legend has it that Doppelbock was the work of monks from the Order of Saint Francis of Paula that had settled in the Munich area. When trying to find a beverage that they could consume while fasting, they created a derivative of the bock style of beer that seemed fuller and richer to the palate. It was as close as liquid bread as they could get.
The brewery founded by these monks? That’d be the Paulaner brewery.
So, while bocks are malty and high in alochol content, doppelbocks can have those same characteristics, with the added benefit of having darker colors and deeper flavors. The brewers out there will know that doppelbocks differ from bocks by having an original gravity of no lower than 1.074, but for you non-brewers out there, it’s not required knowledge.
And Eisbocks? Think concentrated Doppelbock, and you’ll have a good idea of what it’s supposed to taste like. The recipes for Eisbocks traditionally revolve around freezing off some of the water found in Doppelbocks, leaving behind an even deeper malty flavor.
Other bock variants? There are Maibocks (a variant of Bock beers released in May, lighter than traditional bocks), Weisenbocks (Wheat bocks), Weizendoppelbocks (Wheat doppelbocks), and Weisenneisbocks (Wheat ice bock). For the purposes of the BJCP, one should focus on the Maibock, Bock, Doppelbock, and Eisbock. Wheat beers should be judged under different criteria.