The first world war?

According to Christian Wolmar's book Fire and Steam, the railways were hugely important in World War One, shifting men, munitions and materiel the length of Britain.  Of particular importance were the port of Southampton in the south and the long, slow Highland Railway from Perth to Thurso in Scotland.  The Highland was the main supply route for the great naval base at Scapa Flow in Orkney.  All the railways were largely under government control for the entire war, with improved utilisation of resources as a result.

I'm toying with the idea of adding an optional rule in 18GB to reflect the impact of the war.  The rule would apply for one operating round late in the game - perhaps triggered by the first time a 6X train is removed at the end of an OR, or when the first 6X is purchased.  Both Southampton and the Inverness off-board area would generate 5 income more than usual (equivalent to a bonus of 50 in other 18xx games).  I guess the normal bonus routes wouldn't apply for that OR, as a loose representation of the impact of the war on trade, but there would be a special bonus for London to Inverness.  The overall effect would be small but would reward slightly different routes to usual ORs.

I did consider a financial rule as well, to reflect the lack of investment in the railways during this period.  But I think companies should still be allowed to buy trains (otherwise those which have withheld income and/or run as Insolvent will be penalised), and I don't want to limit track building because companies should have the chance to connect to the areas with the new bonuses.   In 1880 China, the communist period stops stock prices from moving, but I don't want that for 18GB because capitalists still made money during the war.  In the end, simplicity is probably best.

One other thing I might do is to add an extra character to the characters variant.  Herbert Walker was chairman of the Railway Executive Committee that directed the contribution of the railways to the war effort.  Wolmar notes that some companies were more affected than others.  So perhaps the player with Herbert Walker could designate up to two companies that would each reduce their income by ten for the OR that represents the war.  (Companies with tokens in Southampton or Perth would be immune).  On the other hand, this might make this card into a Kingmaker role, so perhaps another power might be more appropriate.