Plan 1919 Explained by Ryan Crierie
There are actually several “Plan 1919”s, each done at different times and by different people.
The first one that could be called that, was done by General John E. Capper, and titled Proposals for the Use of Tanks in the Campaign of 1919.
Later, J.F.C. Fuller developed a similar plan titled The Tactics of the Attack as Affected by the Speed and Circuit of the Medium D Tank on 24 May 1918.
After much development by Capper, Fuller, and the War Office; the final version sent to Haig was titled Memorandum on the Requirements for an Armoured Striking Force for an Offensive in 1919.
Sources: Will Add later; this is a quick bash to be expanded later.