The expansion
At around 1900, the economy of central America was on track and imperialism was introduced in central America. It became clear that central America was locked between two powers with greater military strength. So lots of research went into the army, and soon, central American armies, though not not being quantitively superior, were of great qualitative strength, with an artillery brigade for every two infantry divisions. Central American armies also were the first to use gasses in combat, an advantage which gave them a crushing victory in the first Mexican war, winning us a great part of Yucatan.
More important, the first Mexican War was a test of the military strength of the central American republic. Out of this test, the generals concluded that our southern neighbor, Colombia, was ripe for harvesting. War was declared in April 1913, and in a mere two months, central American armies walked among the streets of bogota, so Colombian government offered a lucrative peace deal, which would give us the panama area, along with a great deal of central and western Colombia.
At this time, the central American military didn’t have the strength to defend more land than it already had, so when revanchist Mexicans declared war on the republic in 1918 and in 1927, a defensive policy was followed, staying behind the mountain forts of the los altos area. This ensured very low casualty rates for the republic, while costing mexico half of their population in the repeated attacks.
For Colombia, the case was different, with our armies in camps near bogota, an aggressive defence strategy was developed, so when the alliance of Colombia and equador declared war on the republic, the army reacted with a march on their capitols, seizing them fast, and then waiting for a good peace deal, which gave us the rest of Colombia and a large chunk of equador.
We now had a land border with brazil, a dangerous player in south America, so a defensive position was designed fast. The test of this position came in 1928, when Brazilian troops raced across the jungle, only to be massacred by our artillery. Again, we endured very little casualties.
In the early 1930’s, an uneasy peace came along, and the borders in 1936 were the same as those in 1930, and here they are: