The battle was fought at the location of the modern city of San Lorenzo, Santa Fe which is next to the Paraná River, at the point of its widest flow.
The west bank of the river was tall and steep, forming a natural obstacle, and ships could only land troops and materials on that side of the river using man-made paths cut into the side.
The battlefield was near one of these paths, shaped like a ladder, after which the terrain was a big plain with scattered bushes.
The San Carlos Convent, the main nearby building, was a short distance away from the river.

The location was not an easy place to defend without artillery, as the plains made surprise attacks difficult.
Except for the convent itself, the terrain did not offer any natural barriers that the patriots could exploit.
Nevertheless, the flat terrain was ideal for cavalry manoeuvres, and the distance between the church and the west gully gave enough room for a cavalry charge.
The royalists, on the other hand, could support their troops with their ships from the river.
Without a supporting navy, or local batteries, San Martín had no means to attack the ships.
Although the small path allowed them passage to the ships, it could force the royalist forces to bottleneck during a retreat while the long range guns of the ships protected them.
San Martín studied the battlefield and readied the plan for the operation during the night, when the grenadiers were hidden inside the convent.
The battle was fought at the location of the modern city of San Lorenzo, Santa Fe which is next to the Paraná River, at the point of its widest flow. The west bank of the river was tall and steep, forming a natural obstacle, and ships could only land troops and materials on that side of the river using man-made paths cut into the side. The battlefield was near one of these paths, shaped like a ladder, after which the terrain was a big plain with scattered bushes. The San Carlos Convent, the main nearby building, was a short distance away from the river.
The location was not an easy place to defend without artillery, as the plains made surprise attacks difficult. Except for the convent itself, the terrain did not offer any natural barriers that the patriots could exploit. Nevertheless, the flat terrain was ideal for cavalry manoeuvres, and the distance between the church and the west gully gave enough room for a cavalry charge. The royalists, on the other hand, could support their troops with their ships from the river. Without a supporting navy, or local batteries, San Martín had no means to attack the ships. Although the small path allowed them passage to the ships, it could force the royalist forces to bottleneck during a retreat while the long range guns of the ships protected them. San Martín studied the battlefield and readied the plan for the operation during the night, when the grenadiers were hidden inside the convent.
Battle of San Lorenzo