Final answer:
Sam Houston did not sign an oath of allegiance to the Confederacy, Texans were affected by the Union blockade during the Civil War, and Civil War battles did take place on Texas territory.
Step-by-step explanation:
As governor of Texas, Sam Houston did not sign the oath of allegiance to the Confederacy because by the time Texas seceded in 1861, Houston was no longer governor and he refused to swear loyalty to the Confederacy.
Therefore, the statement is False.
Regarding the effects of the Union blockade along the southern coastline on Texas, it significantly impacted Texas as it disrupted supplies and commerce, which implies that Texans had to protect their coastline.
Thus, the blockade did affect Texas, making the option 'Texans had to protect their coastline' True.
Lastly, Civil War battles did take place on Texas territory, including the Battle of Palmito Ranch, so the statement that Civil War battles did not happen on Texas territory is False.