Petr Agafonov was born in 1908.

He took part in the Nomonhan Incident in 1939, where he flew I-153s in the 22 IAP.

In the morning on 10 July, 22 IAP was in combat in the Huhu-undur-ob area and leitenant Agafonov (I-153) claimed a Ki-27 while leitenant Pavel Solntsev (I-16) claimed a shared together with two other pilots (one of them was possibly leitenant Yakov Kurbatov). Eskadrilya commander kapitan Aleksandr Ivanovich Balashov (I-16) claimed one Ki-27 before he was wounded by a bullet in his abdomen, and he made a forced landing on the steppe. He was taken to hospital where he died of his wounds on 13 July. At the time of his death, Balashov had flown more than ten sorties over Nomonhan and taken part in five air combat.
Leitenant Pavel Mikhailov claimed a shared Ki-27 with another pilot (possibly starshiy leitenant Petr Grayevskiy) but neither place nor time is known.

On 21 August 1939, 22 IAP fought bombers and fighters south-west of Lake Yanhu at around 15:00. Fighters were claimed by leitenant Agafonov (I-153), Vasiliy Smirnov (Polikarpov biplane) and starshiy leitenant Viktor Rakhov. Two Ki-30s were claimed as shared by four pilots flying I-16s; known pilots are leitenant Ivan Krasnoyurchenko and starshiy leitenant Viktor Rakhov.

Over Lake Buir-Nur on 2 September, three Ki-10s from the 33rd Sentai’s 2nd chutai led by 1st Lieutenant Soichi Okamoto, met some reported 30 I-16s. Okamoto claimed the unit’s first four victories of the Incident while Sergeant Major Shozo Saito in vain tried to ram one, but was instead obliged to force-lend.
They had met 22 IAP led by starshiy leitenant Fedor Cheremukhin. This experienced leader rightly reasoned that the I-16 tip 10 had significantly greater speed and firepower, and less manoeuvrability, and initiated the correct tactic for the fight: shooting from further away and avoiding close level manoeuvres. After the skirmish, his unit reported two downed Kawasaki Ki-10s for no own losses.
The encounter again escalated into an air battle. Excellent visibility allowed a great area to be observed, and each engagement was as visible as a flare by pilots on the ground; they immediately scrambled and flew across to assist their comrades. First to arrive were the 1st Sentai Ki-27. More Soviet fighters followed them, and the previous day’s events repeated themselves. The fight developed overhead Hamar-Daba Mountain and the Humurgin-Gol River, at the same levels that offered optimum performance to both sides: 3500 to 5000m. After 45 minutes that had witnessed over 250 machines fighting (175 of them Soviet), the sky grew quiet.
The Japanese admitted losing one Ki-27 when Sergeant Yukio Kijima (Sho-4) of the 1st Sentai was killed and suffering damage to four more fighters and totally claimed seven victories (four by Okamoto).
The Soviets fighters only lost one aircraft and totally claimed eight victories, six of them Ki-27s (reported as a ”I-97”). Known claiming pilots from 22 IAP were leitenant Agafonov (I-153), who claimed a shared Ki-27 together with six other pilots north-west of Lake Uzur-Nur, leitenant Pavel Solntsev (I-16), who claimed two Ki-27s together with five other pilots over squares 531-533 and 633, kapitan Andrey Dekhtyarenko (I-16), who claimed a shared Ki-27 south-east of Lake Uzur-Nur together with three other pilots and kapitan Aleksandr Nikolayev (I-153), who claimed a Ki-27. Leitenant Aleksandr Piskunov (I-153), leitenant Vladimir Garanin (Polikarpov biplane) and mladshiy Viktor Ushakov (I-16) all claimed one shared Ki-27 ”in group”. Kapitan Mikhail Dolbyshev from 56 IAP (I-16) claimed one shared Ki-27 (”in group”).

During the Nomonhan Incident, he flew more than ten combat missions and claimed 2 and 1 shared enemy fighters.

When Germany invade the Soviet Union in June 1941, he served in 12 IAP, which was equipped with I-153s.

He left 12 IAP in September 1941 and was posted to 236 IAP in January 1942. This unit was equipped with Yak-1s.

In February 1943, he was posted to 235 IAD

Agafonov ended the war with 3 biplane victories and a total of 6.
During the war, he was decorated with the Order of the Red Banner (twice), the Order of the Patriotic War 1st Class and the Order of the Red Star.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1939
1	10/07/39	morning	1	Ki-27	Destroyed	I-153		Huhu-undur-ob	22 IAP
2	21/08/39	15:00 ca	1	Ki-27	Destroyed	I-153		SW Lake Yanhu	22 IAP
	02/09/39		1/7	Ki-27	Shared destroyed	I-153		NW Lake Uzur-Nur	22 IAP
	1941
3	23/07/41		1	Hs 126	Destroyed	I-153		NE Yel'nya	12 IAP
	1942
4	18/01/42		1	Ju 88	Destroyed	Yak-1		Dubrovino - Bryukhanovo - Ignatovka	236 IAP
5	11/12/42		1	Bf 109	Destroyed	Yak-1		Balka Peschanaya	236 IAP
6	13/12/42		1	Bf 109	Destroyed	Yak-1		Dubininskiy - Balka Dubovaya	236 IAP

Biplane victories: 3 and 1 shared destroyed.
TOTAL: 6 and 1 shared destroyed.

Sources:
Air War Over Khalkhin Gol: The Nomonhan Incident - Vladimir R. Kotelnikov, 2010 SAM Publications, ISBN 978-1-906959-23-4
All aces of Stalin 1936–1953 – Mikhail Bykov, 2014
Japan Against Russia In The Sky Of Nomonhan - Dimitar Nedialkov, 2005 Propeller Publishing, Sofia, ISBN 954-9367-33-9