Why did the British only send 4 Divisions as initial continent to Fran

[Mike4rest]

It's always puzzled me that Sir John French only took 4 of the 6 available Infantry Divisions to France as

part of the initial BEF when all prewar plans had called for all 6 to go.

They certainly could have used the other two at Mons.

Anyone know the answer as to why only the 4 went?

[Chris_Baker]

It was far from agreed that Britain would send six Divisions, although the planning was based on it. The primary reason not to do so was a concern for home defence. You might find this article useful for background: http://www.1914-1918.net/entente.htm