IN THE latter part of August 1939, events moved rapidly to a climax. On 23rd August Germany signed a pact of non-aggression with the U.S.S.R. This was taken as a warning signal by Great Britain who had already begun preliminary mobilisation, and the Admiralty at once assumed control of all merchant shipping. Great Britain re-affirmed her pledge to Poland on 28th August, having on the previous day stopped the passage of shipping through the Mediterranean until Italy's attitude became clear. On 29th August the Admiralty ordered the fleet to mobilise. Germany invaded Poland at 0445, 1st September, 1939,1 and a few hours later the Admiralty sent out the warning telegram ordering the 'precautionary period.'