Newspapers are valuable sources for researching historical events, most especially those of such national importance as a declaration of war. Register now and view 3 pages for FREE In August of 1939, Britain and Poland signed an agreement of mutual assistance. This mean that were any foreign power to interfere with either country militarily, the other would rush to their aid. Days later, on September 1st, Germany crossed the Polish border under a flag of nationalism, on an invented crusade …