Districts and Forts on the Lines
When the Lines were originally occupied in October 1810, Wellington had divided the First and Second Lines into six districts. This was later increased to seven districts as additional forts were built.
There is little information available on the forts in the fourth line other than the drawings. The original plan was for 60 redoubts but this was reduced to 21.
District number 1; from the Tagus at Alhandra to the Arruda road.
District number 2; from the Arruda road to the left of Monte Agraço
District number 3; from Zibreira to the Caduceira heights
District number 4; from the left of the pass of Runa to the sea
District number 5; from the Tagus to the pass of Bucellas
District number 6; from the pass of Freixal to the park of Mafra
District number 7; from the park at Mafra to the sea.
On the Tagus around St Julian
South of the Tagus from Almada to Trafaria