He was born in 1918 in Uman, Ukraine, as Pinkhus Chesler. His father David was killed in 1921 in a pogrom. Pinkhus became a homeless boy – one of the ca. 6,000,000 homeless children (besprizorniki) in the Soviet Union after the four years of World War I and the three years of the civil war in Russia and Ukraine. He wandered around southern Ukraine. During the national campaign to eliminate homelessness among children, (the peak of which related to 1924-1928), Chesler became a ward of the correctional colony named after Feliks Dzerzhinskii that was headed by the outstanding Ukrainian pedagogue Anton Makarenko. Later, when he was an officer, Chesler kept a portrait of Makarenko hanging on a wall of his cabin.
While studying at a school in Makarenko's colony, Chesler became a worker at the FED photo camera factory, which was under the patronage of the colony. However, the youth dreamed of becoming a sailor. This goal was difficult to attain since he was very small. Nevertheless, due to a recommendation from Makarenko, Chesler was taken on as a ship's boy by the cruiser Chervona Ukraina of the Black Sea Fleet. With his extremely short height, protruding ears and unprepossessing, almost ugly, face, Chesler was the target of jibes on the part of others on board. However, after a short time the mockery ceased because not only could the youth play the bugle, but he was also strong and an expert in fist-fighting (he eventually became bantam weight champion in boxing of the Black Sea Fleet). Nevertheless, for the rest of his naval service he retained the nickname "Malysh" (Russian. for "little boy" or "little fellow").
The captain of the cruiser sent Chesler to naval school, from which he graduated in 1938 with the rank of lieutenant. He was then assigned to serve as second in command of the guard-boat SK-021; subsequently he become its captain. "You have got a ship that fits your size," his comrades teased.
With the beginning of the Soviet-German war in June 1941, Chesler served on the Black Sea. One of his assignments was to accompany and protect evacuation ships, which transported thousands of civilians (more than half of whom were Jewish), who were leaving besieged Odessa for the Caucasus region. Such ships were usually easy targets for enemy bombers and attack planes. Chesler's SK-021 shot down Junkers with its anti-aircraft gun or, when not destroying enemy planes, then at least preventing them from descending and dropping bombs from a low altitude. His SK-021 accompanied not only civil transports, but also military ships carrying Red Army personnel and ammunition for them. Captains often recognized him and his convoy boat, noting with satisfaction: "The malysh is with us today." He was also assigned to detect and destroy enemy torpedo bombers that could land on water and lie in waiting to ambush Soviet sea transports. Chesler was regarded as a very capable and courageous commander of a guard-boat.
In July 1942, while accompanying transport ships that were evacuating people and ammunition from Sevastopol in the Crimea, Chesler was seriously wounded. He spent more than two months in military hospital, but then returned to his naval battalion and to his guard-boat. He was awarded two Orders of the Red Banner.
Chesler lived most of his life in a non-Jewish environment and spoke Russian better than Yiddish. However, when a correspondent of the Yiddish newspaper Eynikayt came to interview him, he introduced himself as Pinkhus, not Piotr, Chesler.
During the landing of the Soviet forces near Kerch, Crimea in November 1943, Senior Lieutenant Chesler was killed by an enemy shell. He was awarded his third order – that of the Patriotic War, I Class, posthumously. He was buried in a military cemetery in Novorossiisk, in the North Caucasus in Russia.