Source A was written by the German chancellor in December 1899. This makes the source reliable because it was written by a high-ranking German official who had first-hand knowledge of what was going on with Germany’s foreign policy. December 1899 was when the naval laws were passed in Germany, and Bulow is speaking to the German parliament in order to try and get these laws passed so that Germany could build up its Navy. The fact that Bulow is discussing Germany’s need for a Navy because of their fear of encirclement shows that perhaps Germany was aggressive in its foreign policy then, and it shows their possible future intentions of attacking other countries.
The tone of the piece is quite aggressive, and a lot of battle talk is used, “the German nation will either be the hammer or the anvil”; Germany will either have to strike or be hit, which could be interpreted as Germany getting ready for battle. However the source may not necessarily be referring directly to war, just the fact that Germany felt they must re-arm and prepare for military expansion in order to toughen up and be ready for any kind of attack, but this is still showing that Germany was aggressive in a way.
Sources 2 and 3 were written from a British point of view. This means that they aren’t very reliable when it comes to the German point of view, as the writers of these sources would not know what was going on with the German side of things, so these sources may not be deemed completely reliable, although they do have some ground as they were written by high-ranking British officials. Both sources are ‘secret memorandums’, so they were not written to have any effect on any one else, so they may be reliable, but because both sources are British, although they are valuable, they are not completely dependable.
Source 2 is saying that Germany had upset many countries around her because of her aggressive approach to foreign policy. Bertie outlines what Germany had done that was part of her foreign policy, for example, “She has beaten and taken money and territory from France.” This violent imagery expresses the fact that Germany was aggressive in her foreign policy 1899-1914.
Source 3 is arguing against the view that German policy was an ‘unchequered record of black deeds’. Sanderson claims that “there have been many occasions on which we have worked comfortably in accord with Germany”, meaning that Germany were not being aggressive at the time but were working fine with other countries. However, there is a slight contradiction later on when Sanderson claims “There have been other times in which she has been extremely aggravating, sometimes unconsciously so, sometimes with intention.” This does show that Germany may have been showing aggression to achieve what she wanted. By February 1907, when the source was written, the first Moroccan Crisis had happened, so this is evidence to back up what Sanderson claimed about Germany being aggressive.
Source 4 is a secret memorandum by Kaiser Wilhelm, which gives the source ground as the Kaiser was one of the key people in German foreign policy. It was written in July 1914, just before war happened and when the Blank Cheque was signed. The tone of the piece is angry, so this is backing up the fact that Germany was aggressive in her foreign policy at the time. However, there was the question on the sanity of the Kaiser, and whether he was actually that influential at all, so this source may only be expressing the aggressive mood of Wilhelm and not Germany in general.
Source 5 is a very exaggerated poem used as propaganda. It was meant to be morale-boosting, and was what was expected at the time after the outbreak of war in 1914. This is not saying anything about German foreign policy, but is about the war. We cannot say that it is supporting the idea that Germany was aggressive about foreign policy at all.
Source 6 is not directly supporting this claim, but we can see that Germany did undergo military expansion from 1880-1914. As it isn’t saying anything about foreign policy at all, then we cannot say this source is reliable and use it as evidence at all.
In conclusion, the general idea of the sources is that Germany was aggressive in its foreign policy from 1899-1914, and also the sources that do back this claim are from reliable people who were involved in dealing with foreign affairs and so would have had a good idea of the situation.