Spain was still recovering manpower after the War of the Spanish Succession and earlier Habsburg-era exhaustion. The new Bourbon order was also imposing political change on the Crown of Aragon. Reinforcements for Cartagena were limited by available manpower as well as political willingness. That shortage increased the importance of local resources and engineering preparation to Lezo and Eslava.
Notable Point · 1:01:17-1:01:47
Why Spain could not simply reinforce Cartagena
Spain's post-succession manpower strain helps explain why Cartagena relied on local resources and fortification work rather than large metropolitan reinforcements.