Due to the technological constraints that the armies in the Age of Lions operate, it has changed the way wars are fought. The basic constraints are that communications are harder since there’s nothing more advanced around than the heliograph, which essentially is using a mirror to reflect sunlight and use it for blinking codes. Most of the time, dispatch riders carry around orders.
Another major issue is logistics, which restrict the movement speed of military forces. Even if travelling on good roads, a larger military unit might only move up to 20 kilometers per day, and good roads are hard to find in this day and age. Ammunition, food, medical supplies and artillery supplies have to be loaded on wagons drawn by horses or oxen. Smaller units on horseback can do better times than this, but at the risk of killing their horses.
Logistics and the lack of long-distance communication lead to concentrating troops into larger units, since smaller units either can’t keep themselves supplied or are unable to contribute significantly since they have no way of communicating with the commanders.
The War of Utö or the Short War or the Stupid War serves as an example of how a war might turn out. Being almost matched in numbers, Hanö and Peimar fought a short war against each other (here you probably want to take a look at the map), with Peimar sending their main army straight towards Halike and Hanö and the Republic of Hanö tried to send their main force towards Somoro in order to go around the border forts in the southwest and hoped that the main force could reach Peimar without encountering resistance.
What happened was a mutual disaster: the Night Witches fought an amazing defensive campaign out in the wilds against three regiments of Hanö troops, forcing the Hanöans to retreat after a week of raids, skirmishes and ambushes. The main force of Peimar besieged Halike and marched southwards towards Hanö, until they were stopped about half the way there by the Hanöan Marine Regiment. While neither side had been dealt a decisive defeat, the war was unpopular in Peimar, Hanö still had reserves left and Peimar was not fully mobilized so Queen Anne I ignored the hawks in her government and brokered a peace.In the end, both Hanö and Peimar ended up feeling good about it since both had won a significant battle.
In this short example, we see the main elements of warfare: maneuver is always a risky proposition, smaller units can beat larger units out in the wilds, battles are not common, fortifications mean a lot and in general, being on the defense is a lot easier than being on the offensive. Battles are also not common and there’s no real concept of front lines, due to the tendency to bunch up units in order to stay in touch.
The infantry does most of the heavy lifting in a war: setting up sieges, defeating the enemy in the field and manning defenses. Artillery supports the infantry. The cavalry has a more exciting role: they are frequently used for scouting, raiding and long-range patrols into enemy territory. The cavalry is also used on the battlefield to charge the infantry, even if this tends to lead to casualties. Specialized cavalry like lancers are the best at this role.
A word about warfare on the seas: most naval action tends to happen near the coast due to the issues with navigation that almost all nations face. Blockading an enemy’s port is what the navy is best at, though there’s no such thing as an absolute blockade: most blockades tend to keep the ships relatively far from the port itself since land-based artillery can be very dangerous to ships, considering land-based artillery tends to be more accurate and have a longer range than shipside cannons. Ships also are used to land troops on islands and along coasts, and used to protect friendly commercial vessels. There’s no law at sea, so a blockading force might well seize or even sink neutral ships. While the Utö war was fought over the island of Utö, there was no real naval action during the entire war, since Hanö had doubts over committing their navy to a blockade in the Archipelago sea and Peimar kept it’s warships in port.