What was the history's most ruthless military strategy?

Personally, I believe that the Maoist genocidal Khmer Rouge regime's use of mass murder throughout its conflict with Vietnam was one of the most horrific military strategies ever used. Their strategy can be succinctly summarised in just three words:

When One Kills Thirty

In April 1975, a Khmer Rouge soldier was seen on the city's streets.

In actuality, this infamous military strategy originated with Pol Pot, the head of the Khmer Rouge faction and a devout supporter of "Mao Zedong Thought" or Chinese Maoism.

He described this kind of military strategy in some poignant terms in an infamous speech given by Radio Phnom Penh on May 15, 1978 [1]:

One of us has to kill 30 Vietnamese, in numbers. likewise, 30,000,000 Vietnamese are equivalent to 1,000,000 Cambodians. To defeat the 50,000,000 Vietnamese, we only need 2,000,000 troops, leaving us with 6,000,000 civilians.

Mr. Saloth Sar, often known as "Comrade Pol Pot," was the ruler of the Khmer Rouge.

Who or what said Pol Pot? "We have to kill 30 Vietnamese, one of us." Additionally, according to his estimates, it would be the ideal way to "crush the 50,000,000 Vietnamese" while also sacrificing the lives of 2,000,000 Cambodians (!)

This purportedly "historical statement" was completely recorded, and it is now abundantly evident that the Extraordinary Chambers in the Courts of Cambodia (ECCC) should continue looking into the heinous crimes committed by the Khmer Rouge.

How did the Khmer Rouge regime implement this harsh military strategy in practise? They really accomplished a "great job" because of the People's Republic of China's strong military backing.

Mrs. Dng Th Niên in front of her damaged village in the province of Tây Ninh

Let's look at the situation in Tân Thành Village in Vietnam's Tây Ninh Province. The Khmer Rouge troops unexpectedly invaded this border community on September 25, 1977.

The community and almost all of the people were destroyed by fire in just a few hours! In the village today, there existed a memorial monument with the Vietnamese description shown below [2]:

It was incredibly brutal; many families, many shelters, including 16, 17 people, were all demolished by the Khmer Rouge troops, who also beheaded, sliced open their bellies, gouged out their livers, tore children into the fire, buried them alive, and slaughtered. 592 persons lost their life in total. 11 teachers were killed at Tân Thành Primary School, which is visible in the backdrop.

Vietnamese victims of the Khmer Rouge government at Tân Thành Village, Tân Lp Commune, and Tân Biên District

Journalists from around the world visited the ruined village of Tân Thành.

Sadly, Tân Thành Village wasn't the only place where the Khmer Rouge committed atrocities. The Khmer Rouge troops raided and pillaged numerous Vietnamese villages, killing every last person inside.

In April 1977, a village in Vietnam's An Giang Province was destroyed.

The savagery of Pol Pot's henchmen claimed 10,000 Vietnamese lives in just four years (1975-1979).

Vietnam suffered at least "79,860 casualties, or 74% of the total number of losses, from Pol Pot and his men's border conflict, according to Lu Văn Li, a Vietnamese official.

Foreign reporters visit the scene of the Ba Chc Massacre in the province of An Giang in 1978

The Khmer Rouge's cruelty peaked on April 18, 1978, when 3,157 Vietnamese residents of the Ba Chc Commune in An Giang Province were massacred using methods that were identical to those used in the Tân Thành Massacre a few months earlier. Witness to the Ba Chc Massacre Mr. Nguyn Văn Knh provided the following account of the crimes committed by the Khmer Rouge [3]:

"All six of my grandchildren and my wife were dead. They took all the jewellery and goods before opening fire. then pushed each group to kill and fire. I was startled to discover numerous dead bodies as I opened my eyes. I was astounded to see my lovely daughter laying still in a pool of blood next to my grandchild feeding on his mother's breast.

Vietnamese soldiers fighting the Khmer Rouge government.

The infamous Ba Chc Massacre served as the primary impetus for both the Vietnamese military's intervention and the overthrow of the Khmer Rouge regime in January 1979, several months later.

Vietnamese had no alternative but to resist the genocidal Maoist regimes in Cambodia in order to save the existence of their country.

Again, I sincerely hope that you readers will learn more about the "One Kill Thirty" strategy that Pol Pot and his Khmer Rouge "comrades" introduced. In any case, it ought to rank among the most severe military strategies ever used. Best regards and thanks for reading my response.