According to the official statement, the Visitor invasion fleet began arriving in Dulu on 069-1117. It was immediately engaged by four Scorpionis Navy fleets, the action being heaviest around the secondary star of the system. Apparently some damage was sustained by colonies around that star -- the Navy reported that the aliens massacred civilian sites as well as engaging legitimate military targets.
The invasion fleet continued to arrive over the next couple of days, and it was not until 072-1117 -- three days after the first hostilities of what is now called The Spinward War -- that fighting finally ended in a victory for Scorpionis.
No mention was made of any Scorpionis military losses, except to say that the battles were ferocious as the Navy had to shield civilian settlements as well as engage in direct fighting.
It was also stated that no prisoners were taken on either side; apparently the aliens do not accept surrender, and fight to the death, sometimes using suicide tactics against critical targets.
There was no information on the nature of the Visitors. We can
still only speculate as to the form of these aliens, and why they have
invaded Yonder so fiercely.