Convincing the King of Thailand to join the war effort was an easy task from the perspective of the German Reich. Whether it was past investments into the region, or the fact that its government employed several German citizens in advisory capacities.
The ties between Germany and the lands of Siam were far greater than those the nation had with the allies. In addition to the reasons already discussed, there was also the fact that there were no armed disputes between the German Reich and the Kingdom of Thailand to speak of.
This could not be said for the British and French who gobbled up territory on both sides of the independent nation's borders in the decades preceding the Great War. In Bruno's past life, Thailand entered the war in the final year, sending some support to the allies in the hopes that these lands would be restored to them.
