diff --git a/src/main/java/mops/gruppen2/domain/Group.java b/src/main/java/mops/gruppen2/domain/Group.java
index 268b439..e5d2e93 100644
--- a/src/main/java/mops/gruppen2/domain/Group.java
+++ b/src/main/java/mops/gruppen2/domain/Group.java
@@ -77,8 +77,4 @@ public class Group extends Aggregate {
             throw new UserNotFoundException("Nutzer wurde nicht gefunden!");
         }
     }
-
-    private void applyEvent(DeleteGroupEvent event) {
-        this.id = this.id * -1;
-    }
 }
diff --git a/src/main/java/mops/gruppen2/service/EventService.java b/src/main/java/mops/gruppen2/service/EventService.java
index 0c1e879..0111ea0 100644
--- a/src/main/java/mops/gruppen2/service/EventService.java
+++ b/src/main/java/mops/gruppen2/service/EventService.java
@@ -6,6 +6,9 @@ import mops.gruppen2.domain.event.Event;
 import mops.gruppen2.repository.EventRepository;
 import org.springframework.stereotype.Service;
 
+import java.util.ArrayList;
+import java.util.List;
+
 @Service
 public class EventService {
     private final SerializationService serializationService;
@@ -48,4 +51,18 @@ public class EventService {
         }
         return tmpId;
     }
+
+    public List<Event> findAllEvents() {
+        Iterable<EventDTO> eventDTOS =  eventStore.findAll();
+        List<Event> events = new ArrayList<>();
+        eventDTOS.forEach(eventDTO -> {
+            try {
+                events.add(serializationService.deserializeEvent(eventDTO.getEvent_payload()));
+            } catch (JsonProcessingException e) {
+                e.printStackTrace();
+            }
+        });
+        return events;
+    }
+
 }
diff --git a/src/main/java/mops/gruppen2/service/GroupService.java b/src/main/java/mops/gruppen2/service/GroupService.java
index dbf8abe..c9ab19d 100644
--- a/src/main/java/mops/gruppen2/service/GroupService.java
+++ b/src/main/java/mops/gruppen2/service/GroupService.java
@@ -1,49 +1,58 @@
 package mops.gruppen2.service;
 
+import lombok.EqualsAndHashCode;
 import mops.gruppen2.domain.Exceptions.EventException;
 import mops.gruppen2.domain.Exceptions.GroupDoesNotExistException;
 import mops.gruppen2.domain.Group;
 import mops.gruppen2.domain.event.CreateGroupEvent;
+import mops.gruppen2.domain.event.DeleteGroupEvent;
 import mops.gruppen2.domain.event.Event;
 import org.springframework.stereotype.Service;
 
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 @Service
 public class GroupService {
 
-    /**
-     * Konstruiert eine vollständige Gruppe aus Events, welche dieselbe Gruppe betreffen.
-     *
-     * @param eventList Die restlichen Events für diese Gruppe
-     * @return Gruppe auf aktuellem Stand
-     */
-    Group buildGroupFromEvents(List<Event> eventList) throws EventException {
-        Group newGroup = new Group();
+    private final EventService eventService;
 
-        try {
-            if (!(eventList.get(0) instanceof CreateGroupEvent)) {
-                throw new GroupDoesNotExistException("Die Gruppe existiert nicht");
+    public GroupService(EventService eventService) {
+        this.eventService = eventService;
+    }
+
+    public List<Group> projectEventList(Map<Long, Group> groupMap, List<Event> events) throws EventException {
+        for (Event event : events) {
+            if (event instanceof CreateGroupEvent) {
+                groupMap.put(event.getGroup_id(), new Group());
+            }
+            if (event instanceof DeleteGroupEvent) {
+                groupMap.remove(event.getGroup_id());
             } else {
-                newGroup.applyEvent(eventList.get(0));
-                eventList.remove(0);
-            }
-            for (Event event : eventList) {
-                if (!(newGroup.getId() > 0)) {
-                    throw new GroupDoesNotExistException("Die Gruppe existiert nicht");
+                try {
+                    Group group = groupMap.get(event.getGroup_id());
+
+                    if (group == null) {
+                        throw new GroupDoesNotExistException("Gruppe " + event.getGroup_id() + " existiert nicht");
+                    }
+
+                    group.applyEvent(event);
+                } catch (EventException e) {
+                    if (e instanceof GroupDoesNotExistException) {
+                        throw e;
+                    }
+                    e.printStackTrace();
                 }
-                newGroup.applyEvent(event);
             }
-        } catch (EventException e) {
-            if (e instanceof GroupDoesNotExistException) {
-                throw e;
-            }
-            e.printStackTrace();
+
         }
 
-        if (newGroup.getId() < 0) {
-            return null;
-        }
-        return newGroup;
+        return new ArrayList<>(groupMap.values());
+    }
+
+    public List<Group> projectEventList(List<Event> events) throws EventException {
+        return projectEventList(new HashMap<>(), events);
     }
 }
diff --git a/src/test/java/mops/gruppen2/builder/EventBuilder.java b/src/test/java/mops/gruppen2/builder/EventBuilder.java
index a06fdf7..99fea37 100644
--- a/src/test/java/mops/gruppen2/builder/EventBuilder.java
+++ b/src/test/java/mops/gruppen2/builder/EventBuilder.java
@@ -21,7 +21,7 @@ public class EventBuilder {
         );
     }
 
-    public static AddUserEvent randomAddUserEvent() {
+    public static AddUserEvent randomAddUserEvent(long group_id) {
         Faker faker = new Faker();
 
         String firstname = faker.name().firstName();
@@ -29,7 +29,7 @@ public class EventBuilder {
 
         return new AddUserEvent(
                 faker.random().nextLong(),
-                faker.random().nextLong(),
+                group_id,
                 faker.random().hex(),
                 firstname,
                 lastname,
@@ -37,11 +37,11 @@ public class EventBuilder {
         );
     }
 
-    public static List<Event> randomAddUserEvents(int count) {
+    public static List<Event> randomAddUserEvents(int count, long group_id) {
         List<Event> eventList = new ArrayList<>();
 
         for (int i = 0; i < count; i++) {
-            eventList.add(EventBuilder.randomAddUserEvent());
+            eventList.add(EventBuilder.randomAddUserEvent(group_id));
         }
 
         return eventList;
diff --git a/src/test/java/mops/gruppen2/domain/GroupTest.java b/src/test/java/mops/gruppen2/domain/GroupTest.java
index 9d9f7da..9130ee5 100644
--- a/src/test/java/mops/gruppen2/domain/GroupTest.java
+++ b/src/test/java/mops/gruppen2/domain/GroupTest.java
@@ -1,6 +1,5 @@
 package mops.gruppen2.domain;
 
-import mops.gruppen2.domain.Exceptions.GroupDoesNotExistException;
 import mops.gruppen2.domain.Exceptions.UserAlreadyExistsException;
 import mops.gruppen2.domain.Exceptions.UserNotFoundException;
 import mops.gruppen2.domain.event.*;
@@ -154,17 +153,4 @@ class GroupTest {
 
         assertThat(group.getDescription()).isEqualTo("Tolle Beschreibung");
     }
-
-    @Test
-    void deleteGroup() throws Exception {
-        CreateGroupEvent createGroupEvent = new CreateGroupEvent(1, 1L, "prof1", "hi", "foo");
-        Group group = new Group();
-        group.applyEvent(createGroupEvent);
-
-        DeleteGroupEvent deleteGroupEvent = new DeleteGroupEvent(44, 1, "loescher78");
-        group.applyEvent(deleteGroupEvent);
-
-        assertThat(group.id).isEqualTo(-1L);
-    }
-
 }
diff --git a/src/test/java/mops/gruppen2/service/GroupServiceTest.java b/src/test/java/mops/gruppen2/service/GroupServiceTest.java
index 0c2e56a..b02f963 100644
--- a/src/test/java/mops/gruppen2/service/GroupServiceTest.java
+++ b/src/test/java/mops/gruppen2/service/GroupServiceTest.java
@@ -10,18 +10,23 @@ import mops.gruppen2.domain.event.Event;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.mockito.configuration.IMockitoConfiguration;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.mock;
 
 class GroupServiceTest {
-    GroupService groupService = new GroupService();
+    GroupService groupService;
 
     @BeforeEach
     public void setUp() {
+        groupService = new GroupService(mock(EventService.class));
     }
 
     @Test
@@ -36,7 +41,7 @@ class GroupServiceTest {
 
 
         Assertions.assertThrows(GroupDoesNotExistException.class, () -> {
-            groupService.buildGroupFromEvents(eventList);
+            groupService.projectEventList(eventList);
         });
     }
 
@@ -48,30 +53,20 @@ class GroupServiceTest {
 
         eventList.add(new DeleteGroupEvent(44, 10, "loescher78"));
 
-        assertThat(groupService.buildGroupFromEvents(eventList)).isEqualTo(null);
+        List<Group> list = new ArrayList<>();
+
+        assertThat(groupService.projectEventList(eventList)).isEqualTo(list);
     }
 
     @Test
-    void firstEventNotCreateGroup() throws Exception {
-        List<Event> eventList = new ArrayList<>();
-
-        eventList.add(new DeleteGroupEvent(44, 10, "loescher78"));
-        eventList.add(new CreateGroupEvent(1, 10L, "prof1", "hi", "foo"));
-
-        Assertions.assertThrows(GroupDoesNotExistException.class, () -> {
-            groupService.buildGroupFromEvents(eventList);
-        });
-    }
-
-    @Test
-    void sucsessfullReturnGroup() throws Exception {
+    void rightClassForSucsessfulGroup() throws Exception {
         List<Event> eventList = new ArrayList<>();
 
         eventList.add(new CreateGroupEvent(1, 10L, "prof1", "hi", "foo"));
 
         eventList.add(new AddUserEvent(900L, 10L, "Ulli", "Ulli", "Honnis", "FC@B.de"));
 
-        assertThat(groupService.buildGroupFromEvents(eventList)).isInstanceOf(Group.class);
+        assertThat(groupService.projectEventList(eventList).get(0)).isInstanceOf(Group.class);
     }
 
 }
\ No newline at end of file