"Breaking the Fortress Line" by Clayron Donnell & "42cm "Big Bertha" and German Siege Artillery" by M. Romanych

I have booked a place on a Holts Tours trip to Liege in August.

Liege (Luttich in German) and its forts, WW1 in blue, WW2 in red (Wikipedia).

Day 1 travel
Day 2 Forts Loncin & Lantin.
Day 3 Forts Eben-Emael & Tancrémont.
Day 4 Antwerp and home.

By coincidence, Clayton Donnell has written a book about the opening moves of World War One. His is a name I know. I have the three books he has written for the Osprey Fortress series, so I did not hesitate to buy his book "Breaking the Fortress Line 1914" published by Pen & Sword.

The book is a straightforward account, starting with the development of the defensive strategies of Belgium, and the more aggresive strategies, Plan XVII in France and the Schlieffen and Moltke plans of Germany. It describes how the Belgians resisted the initial attacks at Liege, the Germans bringing up their Big Berthas and other siege artillery and tackling each fort, one by one, to force the surrender of the fortress of Liege. The Germans then moved up the River Meuse to Namur. French forces had crossed the border into Lorraine and Belgium but were now in retreat. The Germans attacked Namur, then fortresses in  Northern France, such as Longwy and Mauberge. All of this is plotted very well by Donnell, who ends the book with the German siege of Antwerp and the retreat from there by Belgian and British forces.  This is a very good book that concentrates solely on this crucial period of fighting that lasted weeks rather than days, it is well written with lots of maps and photos. I will read it again before the trip.  

This did tweak my curiosity about the German artillery, so I bought an informative, slender book  "42cm Big Bertha and German Siege Artillery of World War 1" by M. Ronamych and M. Rupp. Published by Osprey in their New Vanguard series, it is crammed full of photographs and very good quality drawings, the book details the development and of the using of these beasts, particularly the logistics. All the forts were built to resist artillery up to 21cms. No-one believed a bigger gun would be developed, except the Germans. They decided they had to go through the fortresses of Liege and Namur and of Northern France. In secret they developed the massive guns of 31cm, then 42cm, the latter being named "Big Berthas".

The Germans developed a 30.5cms mortar in the 1890's, nine were built by Krupp between 1898 and 1906. They were good pieces and they served throughout WW1. In 1907, German High Command decided to go a stage further and work was started on 42cm pieces. By August 1914, two Big Berthas had been built and were in testing. These two were withdrawn from the factory and sent to the forces besieging Liege. Eventually, 21 batteries were equipped with either one or two pieces of 30.5cm or 42cm siege artillery. Towards the end of the war, many were destroyed by faulty ammunition. Only three are known to have survived. Two went to USA Aberdeen Proving Ground and were sent for scrap in the 1940's. The third was used by the Wehrmacht in Belgium and Russia in World War 2, but subsequently disappeared. I cannot help myself, this is a great shame, I would love to have seen one.
C'est la guerre.