Political developments in eastern Ukraine have for weeks been dominated by a small, vocal and armed opposition to the interim government in Kiev. Thursday's rallies, by contrast, drew crowds who listened to speeches condemning Russia and resisting the pro-Russian movement that is pushing for autonomy for eastern Ukraine.
Rallies were held in Donetsk, Luhansk, Mariupol and Kramatorsk, where key government buildings have been occupied by pro-Russian groups.
Parliamentary deputy Oleh Lyashko, who is running for office in the May 25 presidential election, rejected charges that Russian speakers in the east had been subject to any discrimination. He also said the armed groups active in the seizures of buildings would not prevail.
"Let those who have weapons be afraid of us, we will fight back. Let the ones who want to split up our country be afraid, because we won't allow them to do it," Lyashko said.
Hromadske television reported that police in Kramatorsk managed to thwart an attempt by pro-Russian activists to attack a pro-unity rally of about 500 people.
Overnight Wednesday, three people were killed and 12 injured after a mob of 300 pro-Russian protesters armed with stun grenades and firebombs tried to seize a National Guard base in the Black Sea port city of Mariupol.
Ukraine's Interior Ministry said shots fired by servicemen in the base initially proved insufficient to deter the mob. There were no casualties among Ukrainian servicemen, the ministry said. At least 63 people involved in the attack were detained, but local media cited police as saying 38 were later released.
Associated Press video filmed outside the base on Wednesday night showed an unidentified man coming out to speak to the armed masked men, who said they wanted no bloodshed. A short while later, however, a crowd of mainly masked young men armed with bats and sticks began throwing Molotov cocktails at the base's gate and the trucks parked in front of it. Sounds of gunfire were heard in response.
One soldier involved in the battle, a 20-year old conscript who gave his name only as Stanislav, said troops were forced to act in self-defense.
"We were attacked by unidentified people and we didn't want to shoot, but they were behaving aggressively," he told the AP. "At first we fired in the air, but they continued advancing."
One protester admitted to a hospital with a bullet wound to the stomach said soldiers opened fire on them while they were attempting to force open the gates.
"We just threw Molotov cocktails to light the way," said Sergei Shevchenko, a 40-year-old businessman from Donetsk.
Residents were divided about the night's events.
"Russia isn't just exporting oil and gas, but also terrorism," said 43-year-old resident Yevgeny Nechiporenko.
Yet passers-by berated Nechiporenko as he spoke, with one accusing him of being an "agent of the West."
"We are willing to give up our lives so long as we don't have to serve the fascists from Kiev," said resident Anna Govorko.
Peter Leonard reported from Donetsk.