By the end of the day I'd put together seven scenarios, and when I got home I gave them all at least one run-though and some of them a more thorough testing.
In 1810, following the May Revolution in Buenos Aires, the newly formed revolutionary government sought to spread its authority across the Viceroyalty of the Río de la Plata. The region of Upper Peru (modern Bolivia), still loyal to the Spanish Crown, became a key target. A Patriot army under Juan José Castelli and Antonio González Balcarce was sent north to defeat royalist forces and rally local support.
Initially, the campaign showed promise. The Patriots had won earlier battles, including the Battle of Suipacha, and occupied parts of Upper Peru. They hoped to inspire a general uprising against Spanish rule. However, internal divisions, overconfidence, and harsh treatment of locals undermined their position. Meanwhile, the Spanish regrouped under General José Manuel de Goyeneche, who had the backing of the Viceroy of Peru and better access to supplies and reinforcements.
By mid-1811, the Patriot army had stalled near Lake Titicaca, and morale was slipping. Despite signs that the Royalists were preparing to attack, the Patriots remained static, underestimating the threat. On 20 June, Goyeneche launched a well-coordinated assault on the Patriot positions near the town of Huaqui.
Both armies had their eastern flank on the shores of Lake Titicaca, whilst each army was split in two by a ridge running north-south through the battlefield. The Patriots were simply formed up in two groups on each side of the ridge. The Royalists deployed some troops on it. The Patriot army was some 5,000 strong, whilst that of the Royalists numbered around 6,000.
Royalists (Attackers)
Patriots (Defenders)
The Patriots were poorly coordinated on each side of the ridge, whilst the Royalists attacked aggressively and exploited the ridge as well as a pass through it to move troops from one side of the field to the other.
The Royalist advance was swift and overwhelming. Patriot attempts to hold the line collapsed, and the army was thrown into full retreat. In just a few hours, the revolutionary army suffered a devastating defeat, losing thousands of men, supplies, and nearly all territorial gains in Upper Peru.
The loss at Huaqui shattered the revolutionary campaign in the north. The Royalists quickly reoccupied Upper Peru, and the Patriot army retreated in disarray. The defeat exposed the weaknesses of the early revolutionary forces and delayed further attempts to liberate the region.
Design Notes
Patriot cavalry seems to have been better used than that of the Royalists, so you'll find that they enjoy an advantage in most scenarios. Winning battles with a sweeping cavalry attack was very much a Patriot thing, as was losing them when that didn't work. With one exception all cavalry is Light Cavalry.