Magisterial, but not a light read. It runs to 832 closely printed pages, plus notes, an index and 40 illustrations. It includes 25 full page battle plans, which would make an excellent guide for a tour of the battlefields.
The key questions are addressed of why the War was fought and why did it continue for as long as it did. Attention is given to the full course of the War, rather than concentrating, as have others, on the better known earlier years.
Whilst the War was continuous, it wasn’t continuous in all areas. Instead the War fell into distinct phases, almost separate wars.
There were both continuing and changing causes. The course of political and constitutional events was dictated by the course of fighting.
The War was preceded by peace in the Empire, the Emperor elected by 3 ecclesiastical and 4 secular Electors. Members of the Habsburg family were elected successively as Emperors and as Kings of Bohemia, the only Imperial Elector who was himself an elected monarch. Stability was maintained through the Peace of Augsburg, which recognised separate Catholic and Lutheran territories.
Imperial peace was disturbed by an aristocratic coup in Bohemia followed by election as King of Bohemia of Frederick, the Calvinist Elector Palatine. This would have altered the Electoral balance with the Calvinist Frederick having two Electoral votes and the Habsburgs none.
The War therefore started in 1618, Frederick and the Bohemian rebels defeated by Bavaria and the Imperialists. Wilson argues this early victory might have ended the War, restoring stability. Instead changes, dynastic and religious, constitutional and territorial, were enforced following victory in the field. Bohemia’s electoral monarchy was converted into a dynastic Habsburg monarchy. Territory was transferred from the Palatine to Bavaria. The Elector Palatine’s electoral status was ceded to the Catholic Duke of Bavaria, again disturbing the Electoral balance.
Opposition to these enforced changes resulted in continuation of the War by the “Protestant Paladins”, who in turn were defeated by the Imperialists. Their defeat was followed by further enforced changes in the Edict of Restitution, which attempted to return to Catholicism ecclesiastical territory assumed by Lutherans and Calvinists subsequent to the Peace of Augsburg. The pattern was repeated. Rather than the War ending, as it might have done, with victory in the field, it continued, as a result of opposition to changes made following that victory , but which disturbed the Empire’s stability.
During the course of the War there were different combatants. The Elector of Saxony fought first in alliance with the Imperialists, then allied with Sweden against them, then changed sides once more to fight for the Empire, and in the final phase was forced into neutrality. Whilst Saxony changed sides, its war aims remained consistent.
Different foreign powers intervened at different times. Denmark and Sweden in turn invaded the Empire. Both sought territory there and hegemony in the Baltic. Denmark invaded in 1625, but by 1629 had been defeated by the Imperialists. Sweden invaded in 1631 and remained a combatant, frequently victorious in battle, until the War ended in 1648. France invaded as an ally of Sweden in 1635. Like Sweden, France remained a combatant until the end of the War, but had different aims. It sought territory in Artois, Lorraine and Alsace, which in due course it took out of the Empire. It also fought to avoid encirclement by the Spanish and Austrian Habsburgs.
Each of the foreign powers recruited (and at different times relied principally on fighting by) German soldiers and allies from within the Empire. Yet such allies had their own war aims. Thus Sweden’s long-term ally, Hessen-Kassel, was focused on its local war against Hessen-Darmstadt.
Recruiters preferred war-seasoned soldiers. This helps explain the practice of victorious armies recruiting from amongst those captured in battle.
The size of armies increased from the beginning of the War, but later declined, partly the result of high mortality amongst soldiers, in particular because of plague and typhus, and difficulties encountered in raising replacement regiments. Armies thus became smaller and their composition changed, as did the nature of warfare, cavalry becoming predominant, able to move quickly and range widely.
Peace was negotiated in Westphalia, from 1644 but not settled until 1648. Representatives spun out negotiations in the hope their negotiating position would be strengthened by victory in the field. This prolonged the fighting, as did difficulties in settling back-pay due to soldiers.