Narrator: This volunteer battalion
has been fighting in Ukraine
since late February.
About half of the members came from other countries.
Narrator: It all started with one Ukrainian man
who they now call Commander.
Narrator: Now, about 700 volunteer fighters
are spread across the country.
Narrator: They call themselves the Carpathian Sich,
after a mountain range that stretches
from the Czech Republic to Romania.
Narrator: The leaders asked us to keep
the exact location they were when we met them
a secret for their safety.
But the group was staying near Kharkiv,
in a village surrounded by Russian forces.
Most people have fled,
but the battalion has been doing what it can
to help the few who stayed.
Narrator: Martin is one of 10 Czechs
who joined this group recently.
The battalion is not part of the Ukrainian military,
but most volunteers say they do have
at least some military experience.
Dozens still want to join,
but finding people who know how to use specific weapons
has been a challenge.
They took us to their current base
inside an abandoned school.
Soldiers patrol the building
and set up sniper lookouts every day.
They sleep in this underground bomb shelter.
Matej, who also came from the Czech Republic,
gave us a tour.
He's just 18, one of the youngest members
of the battalion.
Narrator: The battalion says it's funded by donations,
and even say they have some weapons from foreign armies.
Narrator: These weapons match
the kind the UK gave Ukraine,
but the British army told us they donated directly
to the armed forces of Ukraine,
not to independent battalions.
Leaders wouldn't disclose who was funding them,
or if there have been any deaths,
but there have been injuries.
Narrator: A generator keeps the electricity on,
but there is little comfort.
Narrator: Still, many here say the battalion
has made them feel like they're a part
of something bigger.
Narrator: Life here is scary and uncertain.
Attacks can come at any moment.
Narrator: But it can also be tedious.
Narrator: Martin wanted to come to Ukraine
as soon as Russia invaded.
But it was illegal for Czech citizens
to join the armed forces of another country,
until the prime minister promised
not to prosecute anyone who went to Ukraine.
Leaders from other countries like the UK and Lithuania
have also made clear that volunteers will not be punished
for fighting in the war.
And the Ukrainian government claims
that tens of thousands of foreign fighters
from around the world
have joined an official group of foreign volunteers,
President Zelenskyy's International Legion.
Some members of the group we met,
the Carpathian Sich, tried to join
the official legion at first,
but didn't make the cut.
Narrator: But they say one sentiment
keeps them together.
Narrator: Those words are echoed across the battalion.
This soldier wrote 'Born To Kill Muscovites'
on his helmet.
And for Commander Oleh Kutzin,
it goes back generations.
Narrator: The Commander hopes the battalion
will officially join Ukraine's armed forces.
He says his group has collaborated with them
and is talking about possibilities,
but we couldn't confirm these claims.
Narrator: We reached out
to the Ministry of Defense of Ukraine
but didn't hear back.
Regardless of the battalion's status with the army,
many members told us there's no turning back.