In a rare interview on Sunday, the 70-year-old elite soldier broke decades of silence to call on troops to disobey orders for the pullout, saying Sharon must have lost his mind to order Israel's first ever withdrawal from Palestinian land.
"My comrade has lost all reason," the Maariv newspaper quoted Har Tzion, who with Sharon co-founded the infamous Paratrooper Unit 101 that operated deep behind Israeli lines in the 1950s, as saying.
"The great fighter has decided to run away," added the man hailed by the late Moshe Dayan, a former general and defence minister as the bravest Jewish fighter in centuries.
Echoing recent calls from right-wingers, Har Tzion lambasted the Gaza pullout plan as a "shoah" - the Hebrew word for catastrophe that also denotes the Holocaust.
On Friday, Israeli police opened an inquiry into ultra-nationalist calls for violent resistance to the planned forced removal of settlers from Gaza and four small settlements in the West Bank, after speakers at a thousands-strong Jerusalem meeting also accused Sharon of leading the nation to a "shoah".
The creation of such a [Palestinian] state would signal "the beginning of the end" for Israel
Regarded by Israelis as the best Jewish fighter since the Roman revolt
Despite saying Israeli soldiers cannot be held responsible for the planned withdrawal, Har Tzion said troops must disobey orders for the pullout and pay the price that any such refusal entails - namely court martial and prison.
Covered in scars and never fully recovered from his combat experience, the often caricatured commando has lived as a loner for half a century in a ranch at the foot of the Belvoir citadel that dominates the Jordan valley.
Like his friend of decades, Sharon on his ranch in the Negev desert, he raises prize cows for local agricultural fairs.
Several hundred cows roam the wind-swept hillside, home to the ranch - renamed after his sister Shoshana (Rose) who was allegedly killed after hiking across the Jordanian border decades ago.
A fervent believer of an eye for an eye, Har Tzion and three of his comrades crossed Jordanian lines to slit the throats of four Arab bedouins allegedly in revenge.