According www.geacron.com, between 8 BCE and 10 CE, it shows the annexation of Germania, particularly the with the tribes of the Frisii, Cherusci, Chatti and others for about 2 decades, however, doing some limited reseach only shows that there was extensive conflicts between the Romans and the Germanics (particularly the Frisii would be successful against the Romans), however I can find no mention of political incursion or annexation of territory, nor is the territory mentioned to be annexed in any other anachronistic map.
Is this a mistake by the resource, or were these territories of Germania at one point indeed considered annexed territories of the new Empire? What were the circumstances around this, and what led to its quick downfall? Why weren't more attempts made to regain (or indeed retain before fully losing it in the first place) such a vast territory?
PART ONE: INITIAL CONTACTS
Roman involvement in Germania begins with Caesar in the 50s BCE, when peoples from across the Rhine continually interfered with or migrated into the midst of his 'conquest' of the Gallic nations. He bridged the Rhine in 55 BCE and briefly marauded there, before coming back to Gaul.
After Octavian defeated Antonius at Actium in 31 BCE, he sent his right-hand-man Agrippa to Gaul to finish the pacification of the peoples there, who had become quite rebellious in the decades since Caesar departed. In a series of wars in the 30s and early 20s BCE, it became clear to the Romans that the problems were being caused in some part by elements across the Rhine, and that some interference in Germania was going to be necessary to ensure the pax Romana in Gaul. There were Germanic peoples living on both sides of the river, which waterway had proven to be more symbolic than physical as a boundary. In 27 BCE Octavian officially set up Gaul as a province, but the situation did not improve. The Gallic tribes continued to bicker with one another, often at Germanic instigation, and Germanic trans-Rhine raids on the Gauls continued (just as the had for centuries previous; raiding was a basic element of their culture, and had suddenly become incompatible with the new Gaul).
There were some attempts at diplomacy, with limited success, but ultimately doomed because there was no monolithic "German" state, but many small and mobile Germanic tribes. There was a treaty with the powerful Chatti tribe (Dio 64.36), but it wasn't enough to counteract the others. In 17-16 BCE, the Sugambri, Tencteri, and Usipetes poured over the Rhine, ambushed and defeated a Roman force under Lollius, and plundered the new Gallic province. Augustus hurried there to assess the damage (which was more to Roman pride than to any physical losses). By the time he got there, the Germans had melted away back across the Rhine and there was nothing but empty woods and burning farms.
Augustus stayed there in Gaul for three years, perhaps splitting his time between the Rhine frontier and Provence. In that time, Roman presence in Gaul was massively bolstered, and six legionary forts were established along the Lower Rhine. When he returned to Rome in 13 BCE, he left his stepson Drusus in charge. That year (or perhaps in 12), Drusus began a massive campaign against the Germanic peoples. He caught the the Sugambri by themselves on the Gallic side of the river and inflicted a defeat on them, then crossed the Rhine and delivered a similar strike on the Tencteri. There were Roman amphibious raids on the North Sea coast, and in conjunction further penetrations into the heart of Germany, where no Roman had gone before. He defeated the Usipetes at their "homeland," bridged the Lippe river, and through the Cherusci as far as the Weser river. He then returned to the Rhine for winter quarters, but left a garrison at the junction of the Lippe and Eliso rivers, and another in the territory of the Chatti near the Rhine. For this action he was awarded a triumph back in Rome.
There has been some debate about the motivation of these actions, but I am not one that supports raw aggression (conquest) as the basis. German-instigated disturbances in Gaul had continued right up until Drusus took action, strongly suggesting that the Romans had decided that offensive action was necessary to ensure the Gallic pax Romana. Urbanization was already rapidly advancing in Gaul, and it seems clear that the Romans recognized just how valuable and powerful the place could be (and would be for the next 2000 years!)
In 11-10 BCE, Augustus returned to the frontier to join Drusus. There was another campaign against the Sugambri and the Chatti, who abandoned lands awarded to them in an attempt to pacify them previously. In 9 BCE, Drusus again attacked, again hitting the Chatti and defeating the Marcomanni. He pushed across the Weser and reached the Elbe. He then turned back towards the Rhine, broke his leg along the way, and died before reaching the frontier. The Romans spun these series of invasions as successes, but it is unclear what was accomplished. Certainly the Germans had to have been intimidated more than they had been since 55 BCE, when Caesar paid a visit. Most of the German tribes near the Rhine had no doubt heard stories about Caesar's legions in Gaul, but few had actually fought against Romans. It isn't at all clear if the Romans left permanent outposts there -- archaeology has revealed several forts along the Lippe, but dating is elusive and they could belong to a later period.