To make a miniature Siamese army is to build some toy war elephants. Even if they did not play a deciding role in most historical battles, war elephants remained the prized symbol of (royal) military might well into the modern age (as seen in the 1866 photograph above) and would similarly feature as the major point of interest for your miniature Siamese army.
The war elephant allowed royalty and generals to engage in battle with each other in Homeric fashion. The classic arrangement as described in Thai military manuals was to have the high-status warrior sit in the front where we would normally expect the mahout or elephant driver to be. He or she would be helped by two soldiers who could be found further back on the elephant. One would sit on a raised dais that functioned as an open howdah cum armoury where an assortment of pole weapons were kept; the other would be the mahout who directed the elephant's movements from the rear. The difference between this classic arrangement with a 3-man crew and the four-man crew shown in the 1866 photograph above may be the addition of a hand-gunner (possibly the second man from the right in the photo).
The war elephant and its crew was to be protected by an elephant guard of four infantrymen who would take up station near to the side of each elephant leg. This was a practice that can be traced back to c. A.D. 1200 at least, as this artifact shows:
Here are some of the war elephant monuments found in Thailand:
Not entirely surprisingly, 1/72 or 20mm Siamese war elephants are not available commercially. I will therefore have to make some myself and the current plan is to use the 1/72 HäT Macedonian and Indian elephant sets (both of which feature Asian elephants) as base and build the rest. Should be fun!
Those of you who are interested in colonial gaming may even consider this hybrid option, as seen in a 1900 photo: