Translation of "Guarding" in Spanish

Someone is guarding the entrance.

Alguien está vigilando la entrada.

The soldiers were guarding the bridge.

Los soldados vigilaban el puente.

With his fleet guarding his flank, the Roman general reaches within 15km of the Ebro.

Con su flota resguardando su flanco, el general romano llega a estar 15kms del Ebro.

His role was to support Marshal Oudinot in  guarding the northern flank of the French salient.  

Su papel era apoyar al mariscal Oudinot en la protección del flanco norte del saliente francés.

And guarding the road to Paris. But by now he  was showing signs of exhaustion and disillusion.

y protegiendo el camino a París. Pero ahora mostraba signos de agotamiento y desilusión.