diff --git a/src/Dao/SnapshotDao.php b/src/Dao/SnapshotDao.php
index 57e5fafb..7f41293a 100644
--- a/src/Dao/SnapshotDao.php
+++ b/src/Dao/SnapshotDao.php
@@ -48,7 +48,7 @@ class SnapshotDao extends AbstractDao
 
 	private function getUser(Snapshot $snapshot)
 	{
-		$userId =  $snapshot->getUserId();
+		$userId = $snapshot->getUserId();
 		return $this->userDao->findById($userId);
 	}
 }
diff --git a/src/Services/HistoryService.php b/src/Services/HistoryService.php
index 52b92f98..cd784f9d 100644
--- a/src/Services/HistoryService.php
+++ b/src/Services/HistoryService.php
@@ -42,28 +42,43 @@ class HistoryService
 			$snapshot->setTime($this->timeService->getCurrentTime());
 			$snapshot->setUser($this->authService->getLoggedInUser());
 
-			$lastSnapshot = $this->getLastSnapshot($snapshot);
+			$earlierSnapshots = array_values($this->snapshotDao->findEarlierSnapshots($snapshot));
+			$snapshotsLeft = count($earlierSnapshots);
 
-			$dataDifference = $this->getSnapshotDataDifference($snapshot, $lastSnapshot);
-			$snapshot->setDataDifference($dataDifference);
-
-			if ($snapshot->getOperation() !== Snapshot::OPERATION_DELETE && $lastSnapshot !== null)
+			while (true)
 			{
-				//don't save if nothing changed
-				if (empty($dataDifference['+']) && empty($dataDifference['-']))
-				{
-					if ($snapshot->getId())
-						$this->snapshotDao->deleteById($snapshot->getId());
-					return $lastSnapshot;
-				}
+				$lastSnapshot = array_shift($earlierSnapshots);
+				$dataDifference = $this->getSnapshotDataDifference($snapshot, $lastSnapshot);
+				$snapshot->setDataDifference($dataDifference);
 
-				//merge recent edits
+				if ($lastSnapshot === null)
+					break;
+
+				//recent snapshots should be merged
 				$isFresh = ((strtotime($snapshot->getTime()) - strtotime($lastSnapshot->getTime())) <= 5 * 60);
-				if ($isFresh && $lastSnapshot->getUserId() === $snapshot->getUserId())
-				{
-					$lastSnapshot->setData($snapshot->getData());
-					return $this->saveSnapshot($lastSnapshot);
-				}
+				if (!$isFresh || $lastSnapshot->getUserId() !== $snapshot->getUserId())
+					break;
+
+				//delete the current snapshot
+				if ($snapshot->getId())
+					$this->snapshotDao->deleteById($snapshot->getId());
+
+				//become previous snapshot, but keep the current data
+				$snapshot->setId($lastSnapshot->getId());
+				if ($snapshot->getOperation() !== Snapshot::OPERATION_DELETE)
+					$snapshot->setOperation($lastSnapshot->getOperation());
+
+				-- $snapshotsLeft;
+			}
+
+			$onlyRemovalLeft = (!$snapshotsLeft && $snapshot->getOperation() === Snapshot::OPERATION_DELETE);
+
+			$emptyDiff = (empty($dataDifference['+']) && empty($dataDifference['-']));
+			if ($onlyRemovalLeft || $emptyDiff)
+			{
+				if ($snapshot->getId())
+					$this->snapshotDao->deleteById($snapshot->getId());
+				return array_shift($earlierSnapshots);
 			}
 
 			return $this->snapshotDao->save($snapshot);
@@ -110,10 +125,4 @@ class HistoryService
 			'-' => $diffFunction($oldData, $newData),
 		];
 	}
-
-	private function getLastSnapshot(Snapshot $reference)
-	{
-		$earlierSnapshots = $this->snapshotDao->findEarlierSnapshots($reference);
-		return empty($earlierSnapshots) ? null : array_shift($earlierSnapshots);
-	}
 }
diff --git a/tests/Services/HistoryServiceTest.php b/tests/Services/HistoryServiceTest.php
index 59770654..bc76d588 100644
--- a/tests/Services/HistoryServiceTest.php
+++ b/tests/Services/HistoryServiceTest.php
@@ -123,6 +123,7 @@ final class HistoryServiceTest extends AbstractTestCase
 	public static function mergingProvider()
 	{
 		{
+			//basic merging
 			$oldSnapshot = new Snapshot(1);
 			$oldSnapshot->setTime(date('c', 1));
 			$oldSnapshot->setOperation(Snapshot::OPERATION_CREATION);
@@ -139,10 +140,11 @@ final class HistoryServiceTest extends AbstractTestCase
 			$expectedSnapshot->setData(['new' => '2']);
 			$expectedSnapshot->setDataDifference(['+' => ['new' => '2'], '-' => []]);
 
-			yield [$oldSnapshot, $newSnapshot, $expectedSnapshot, date('c', 3)];
+			yield [[$oldSnapshot], $newSnapshot, $expectedSnapshot, date('c', 3), [2]];
 		}
 
 		{
+			//too big time gap for merge
 			$oldSnapshot = new Snapshot(1);
 			$oldSnapshot->setOperation(Snapshot::OPERATION_CREATION);
 			$oldSnapshot->setData(['old' => '1']);
@@ -157,10 +159,11 @@ final class HistoryServiceTest extends AbstractTestCase
 			$expectedSnapshot->setData(['new' => '2']);
 			$expectedSnapshot->setDataDifference(['+' => ['new' => '2'], '-' => ['old' => '1']]);
 
-			yield [$oldSnapshot, $newSnapshot, $expectedSnapshot, date('c', 3000)];
+			yield [[$oldSnapshot], $newSnapshot, $expectedSnapshot, date('c', 3000), []];
 		}
 
 		{
+			//operations done by different user shouldn't be merged
 			$oldSnapshot = new Snapshot(1);
 			$oldSnapshot->setOperation(Snapshot::OPERATION_CREATION);
 			$oldSnapshot->setData(['old' => '1']);
@@ -177,10 +180,11 @@ final class HistoryServiceTest extends AbstractTestCase
 			$expectedSnapshot->setDataDifference(['+' => ['new' => '2'], '-' => ['old' => '1']]);
 			$expectedSnapshot->setUserId(null);
 
-			yield [$oldSnapshot, $newSnapshot, $expectedSnapshot, null];
+			yield [[$oldSnapshot], $newSnapshot, $expectedSnapshot, null, []];
 		}
 
 		{
+			//merge that leaves only delete snapshot should be removed altogether
 			$oldSnapshot = new Snapshot(1);
 			$oldSnapshot->setOperation(Snapshot::OPERATION_CREATION);
 			$oldSnapshot->setData(['old' => '1']);
@@ -189,35 +193,91 @@ final class HistoryServiceTest extends AbstractTestCase
 			$newSnapshot->setOperation(Snapshot::OPERATION_DELETE);
 			$newSnapshot->setData(['new' => '2']);
 
+			yield [[$oldSnapshot], $newSnapshot, null, null, [2, 1]];
+		}
+
+		{
+			//chaining to creation snapshot should preserve operation type
+			$oldestSnapshot = new Snapshot(1);
+			$oldestSnapshot->setOperation(Snapshot::OPERATION_CREATION);
+			$oldestSnapshot->setData(['oldest' => '0']);
+
+			$oldSnapshot = new Snapshot(2);
+			$oldSnapshot->setOperation(Snapshot::OPERATION_CHANGE);
+			$oldSnapshot->setData(['old' => '1']);
+
+			$newSnapshot = new Snapshot(3);
+			$newSnapshot->setOperation(Snapshot::OPERATION_CHANGE);
+			$newSnapshot->setData(['oldest' => '0', 'new' => '2']);
+
+			$expectedSnapshot = new Snapshot(1);
+			$expectedSnapshot->setOperation(Snapshot::OPERATION_CREATION);
+			$expectedSnapshot->setData(['oldest' => '0', 'new' => '2']);
+			$expectedSnapshot->setDataDifference(['+' => ['oldest' => '0', 'new' => '2'], '-' => []]);
+
+			yield [[$oldSnapshot, $oldestSnapshot], $newSnapshot, $expectedSnapshot, null, [3, 2]];
+
+			$newSnapshot = clone($newSnapshot);
+			$newSnapshot->setId(null);
+			yield [[$oldSnapshot, $oldestSnapshot], $newSnapshot, $expectedSnapshot, null, [2]];
+		}
+
+		{
+			//chaining to edit snapshot should update operation type
+			$oldestSnapshot = new Snapshot(1);
+			$oldestSnapshot->setOperation(Snapshot::OPERATION_CREATION);
+			$oldestSnapshot->setData(['oldest' => '0']);
+			$oldestSnapshot->setTime(date('c', 1));
+
+			$oldSnapshot = new Snapshot(2);
+			$oldSnapshot->setOperation(Snapshot::OPERATION_CHANGE);
+			$oldSnapshot->setData(['old' => '1']);
+			$oldSnapshot->setTime(date('c', 400));
+
+			$newSnapshot = new Snapshot(3);
+			$newSnapshot->setOperation(Snapshot::OPERATION_DELETE);
+			$newSnapshot->setData(['new' => '2']);
+			$newSnapshot->setTime(date('c', 401));
+
 			$expectedSnapshot = new Snapshot(2);
 			$expectedSnapshot->setOperation(Snapshot::OPERATION_DELETE);
 			$expectedSnapshot->setData(['new' => '2']);
-			$expectedSnapshot->setDataDifference(['+' => ['new' => '2'], '-' => ['old' => '1']]);
+			$expectedSnapshot->setDataDifference(['+' => ['new' => '2'], '-' => ['oldest' => '0']]);
+			$expectedSnapshot->setTime(date('c', 402));
 
-			yield [$oldSnapshot, $newSnapshot, $expectedSnapshot, null];
+			yield [[$oldSnapshot, $oldestSnapshot], $newSnapshot, $expectedSnapshot, date('c', 402), [3]];
+
+			$newSnapshot = clone($newSnapshot);
+			$newSnapshot->setId(null);
+			yield [[$oldSnapshot, $oldestSnapshot], $newSnapshot, $expectedSnapshot, date('c', 402), []];
 		}
 	}
 
 	/**
 	 * @dataProvider mergingProvider
 	 */
-	public function testMerging($oldSnapshot, $newSnapshot, $expectedSnapshot, $currentTime)
+	public function testMerging($earlierSnapshots, $newSnapshot, $expectedSnapshot, $currentTime, $expectedDeletions = [])
 	{
 		$this->timeServiceMock->method('getCurrentTime')->willReturn($currentTime);
 
 		$this->snapshotDaoMock
+			->expects($this->once())
 			->method('findEarlierSnapshots')
-			->will(
-				$this->onConsecutiveCalls([$oldSnapshot], null));
+			->willReturn($earlierSnapshots);
 
 		$this->snapshotDaoMock
-			->expects($this->once())
+			->expects($this->exactly($expectedSnapshot === null ? 0 : 1))
 			->method('save')
 			->will($this->returnCallback(function($param) use (&$actualSnapshot)
 				{
 					$actualSnapshot = $param;
 				}));
 
+		$this->snapshotDaoMock
+			->expects($this->exactly(count($expectedDeletions)))
+			->method('deleteById')
+			->withConsecutive(...array_map(function($del) { return [$del]; }, $expectedDeletions));
+
 		$historyService = $this->getHistoryService();
 		$historyService->saveSnapshot($newSnapshot);
 		$this->assertEntitiesEqual($expectedSnapshot, $actualSnapshot);