After the overthrow of the government of Urbano Rattazzi, because of the popular indignation at the events in Aspromonte, the new prime minister Luigi Carlo Farini encouraged Nullo to form a legion of volunteers to intervene on the side of Polish insurgents against Russian domination, ensuring his lobbying at King Vittorio Emanuele II, to declare war on the Russian Empire.
Nullo, already friends with Poles such as Ludwik Mierosławski and Marian Langiewicz, who supported him and Garibaldi in their past fights, quickly took to the Polish cause, soon organizing meetings in Bergamo and recruiting volunteers for the Polish cause, recalling Polish support for the Italian cause during the Napoleonic wars (Polish Legions in Italy), and even more so, during the Spring of Nations (Mickiewicz's Legion).

Farini was considered insane and forced to resign, but Nullo could leave for Poland, gathering some Italian volunteers (sources vary with regards to their number, but most reliable ones settle on about twenty).
The group, commanded by Nullo, became known as the Garibaldi Legion.
During the trip, the Italian group was joined by a small groups of Polish emigres and the French volunteer unit, the Zouaves of Death, led by Lieutenant François Rochebrune.
The Italians and the French were sometimes referred to as the Foreign Legion.

Nullo with a selected cadre of a dozen or so volunteers reached Kraków in April 1863.
They were incorporated into the unit of colonel Józef Miniewski.
The Legion crossed the borders of Congress Poland on the night of 3–4 May near Ostrężnica and Czyżówka, after organizing in Krzeszowice.
Early in the morning of the 4th the unit's first battle in Poland occurred at Podłęże where it defeated a Russian force (the garrison from Olkusz).
The Polish National Government awarded him the rank of general.
With a Polish unit commanded by colonel Miniewski he marched on Olkusz.
On the morning of 5 May they reached Krzykawka.

Subsequently, on 5 May, the Legion, along with the Polish unit under Miniewski, took part in the Battle of Krzykawka.
In the first stage of the battle, the insurgents push the Russian troops back in close fighting; but subsequent Russian reinforcements turned the tide and the insurgents and their foreign allies suffered heavy casualties; both Miniewski and Nullo were killed in that battle.
Nullo was mortally injured leading the charge.
Hit by a Cossack bullet while preparing (or leading) a charge (sources vary), he had only time to whisper, in Bergamo dialect: So' mort! (
I'm dead).
Several other Italians were killed in this battle, and some were taken prisoner and deported to Siberia, including the cornigliese Giovanni Rustici.
After the overthrow of the government of Urbano Rattazzi, because of the popular indignation at the events in Aspromonte, the new prime minister Luigi Carlo Farini encouraged Nullo to form a legion of volunteers to intervene on the side of Polish insurgents against Russian domination, ensuring his lobbying at King Vittorio Emanuele II, to declare war on the Russian Empire. Nullo, already friends with Poles such as Ludwik Mierosławski and Marian Langiewicz, who supported him and Garibaldi in their past fights, quickly took to the Polish cause, soon organizing meetings in Bergamo and recruiting volunteers for the Polish cause, recalling Polish support for the Italian cause during the Napoleonic wars (Polish Legions in Italy), and even more so, during the Spring of Nations (Mickiewicz's Legion).
Farini was considered insane and forced to resign, but Nullo could leave for Poland, gathering some Italian volunteers (sources vary with regards to their number, but most reliable ones settle on about twenty). The group, commanded by Nullo, became known as the Garibaldi Legion. During the trip, the Italian group was joined by a small groups of Polish emigres and the French volunteer unit, the Zouaves of Death, led by Lieutenant François Rochebrune. The Italians and the French were sometimes referred to as the Foreign Legion.
Nullo with a selected cadre of a dozen or so volunteers reached Kraków in April 1863. They were incorporated into the unit of colonel Józef Miniewski. The Legion crossed the borders of Congress Poland on the night of 3–4 May near Ostrężnica and Czyżówka, after organizing in Krzeszowice. Early in the morning of the 4th the unit's first battle in Poland occurred at Podłęże where it defeated a Russian force (the garrison from Olkusz). The Polish National Government awarded him the rank of general. With a Polish unit commanded by colonel Miniewski he marched on Olkusz. On the morning of 5 May they reached Krzykawka.
Subsequently, on 5 May, the Legion, along with the Polish unit under Miniewski, took part in the Battle of Krzykawka. In the first stage of the battle, the insurgents push the Russian troops back in close fighting; but subsequent Russian reinforcements turned the tide and the insurgents and their foreign allies suffered heavy casualties; both Miniewski and Nullo were killed in that battle. Nullo was mortally injured leading the charge. Hit by a Cossack bullet while preparing (or leading) a charge (sources vary), he had only time to whisper, in Bergamo dialect: So' mort! (I'm dead). Several other Italians were killed in this battle, and some were taken prisoner and deported to Siberia, including the cornigliese Giovanni Rustici.
Francesco Nullo