Madrid, Oct. 8--The conservative Spanish government, fighting for its existence against the combined assault of extremists in every quarter of the Young Republic, appeared today to have gained complete mastery over the largest rebel strongholds.

Lisbon, Portugal, Oct. 7--The Portuguese authorities today ordered the frontier closed because of the Spanish rebellion.

Washington, Oct. 7 All Americans residing in Spain are safe, according to advice transmitted by Ambassador Claude Bowers from Madrid to the State Department here.

The Department announced that Bowers is in close touch with the American Consuls in the Spanish cities, and that so far no Americans have suffered injuries or been subjected to inconveniences.