But at 39, two years after enlisting, he gave up the fight for health reasons in March.
His frozen shoulder caused stiffness and pain, and engaging in combat felt irresponsible, he said, as it could have put his fellow troops in danger.
It was not an easy decision to make. As a Belarusian fighter-turned-civilian, Tamashevich has no right to work, rent an apartment, or open a bank account in Ukraine.
According to the current Ukrainian law, foreign fighters with no residence permit have seven days to leave Ukraine after they break their army contract.
Several Belarusians have joined the war against Russia, in the hope that President Vladimir Putin’s fall would also bring down his main ally – Belarus’s President Alexandr Lukashenko.
Returning home would mean imprisonment.
There is a glimmer of hope for Tamashevich, though.
The Ukrainian Parliament has passed in a first reading a new bill which would allow Belarusian and pro-Ukraine Russian fighters to apply for Ukrainian passports as long as they give up their first citizenship. They would receive residence permits, but is unclear when the new rules may come into force.
Tamashevich arrived in Ukraine in 2021, after Belarus launched a case against him for taking part in mass protests a year earlier against alleged electoral fraud committed by Lukashenko.
To stay in Ukraine, he applied for asylum eight months ago. But he is still waiting for a decision.
“The fact that I fought in the Ukrainian army does not matter. I spoke to the SBU [Security Service of Ukraine] officers who deal directly with Belarusians but these are completely separate branches of the government,” Tamashevich recently told Al Jazeera, in a cafe in Kyiv. “Trying to influence my case would count as corruption. This is how democracy works.”
But he does not complain. He has managed to save up some money to survive until the asylum decision, and meanwhile focuses on volunteering.
Once his health improves, he may return to the front.
It is unclear how many Belarusians currently fight in Ukraine, but according to unofficial numbers, it could be up to 1,000. More than 40 people have lost their lives in combat, according to the Kyiv Independent news outlet.
The Association of Belarusian Veterans of the Ukraine War, a foundation registered in Warsaw in 2023 by Belarusian activist Pavel Maryeuski, says most Belarusian veterans are currently in Poland, a country which has embraced Belarusians fleeing repressions over several decades.
Maryeuski, who is in his 30s, is also a veteran.
After leaving a Belarusian regiment following six months of service in 2022, he wanted to remain in Kyiv and help as a volunteer. But staying proved harder than he expected.
“I came to the migration service and they kicked me out because I am Belarusian, and for them, I am from an aggressor state. It did not help that I fought for Ukraine” said Maryeuski.
He moved to Poland and soon realised that the life of an exiled Belarusian veteran was far from rosy. Many have struggled to legalise their stay, find a job, or return to civilian life far from the Ukrainian front lines.
“A person can come back from the war, but the war doesn’t leave a person as easily. I’ve faced it myself. The sounds of airplanes and trams in Warsaw scared me at first,” he said.
“A psychologist agreed to work with me for free for which I will always be grateful. But those who do not receive psychological assistance are left alone with their problems. And the solution they find is usually alcohol or drugs.”
Maryeuski, along with his fellow former fighters, opened the foundation to address their shared challenges. Its group chat has more than 100 members who support and check on one another.
Maxim, 25, who requested anonymity, is a member.
He escaped a prison sentence for participating in antigovernment protests in Belarus and crossed into Ukraine in 2021.
As the Belarusian authorities had his passport, he could not regularise his stay in Ukraine.
After Russia launched the full-scale invasion in late February 2022, he joined a Belarusian unit three days after the war began and fought until October 2022. He quit in part because losing comrades proved hard to bear, he said.
But without documents, he could not stay in Ukraine.
With a passport copy and birth certificate in hand, he crossed into Poland, where – after several hours of security checks at the border – he claimed asylum.
At first, he sought help from his friends because he could not work legally while awaiting the asylum decision. The welfare support he received from the Polish state was not enough to cover his expenses.
He received refugee status six months later, but believes that more support for Belarusian veterans should be available.
“Poland should create some sort of support system but it is unlikely that it will be put in place unless something major happens in Belarus,” he said. “For the moment, there is no help out there, so you have to take care of yourself all alone.”
One year into the creation of the Association of Belarusian Veterans of the Ukraine War, Maryeuski feels “abandoned”.
No one seems to care about the fate of his comrades, he said. Over the past year, they have not received a single donation.
They fund psychological and medical assistance for veterans by chipping in or with the help of the Belarusian By-Sol foundation.
“We applied for funding from several organisations, but we were not successful. As I was told in an informal conversation, European and Belarusian independent organisations do not want to fund us as they think we are combatants involved in the war,” Maryeuski said.
“Some of the guys are still young, even 18 or 19. They have their lives ahead of them. We have to help them.”