When Lincoln sent food supplies to Fort Sumner. Why did he inform the confederacy that he would not be sending troops or weapons
There seems to be a confusion in your question.
There was no fort called Fort Sumner during the American Civil War. However, there was a fort named Fort Sumter that is relevant to your query.
In the context of Fort Sumter, President Abraham Lincoln did not send food supplies to the Confederate forces occupying the fort; instead, he tried to send reinforcements to the fort. In April 1861, as tensions between the Union and Confederate forces escalated, Fort Sumter, located in South Carolina, was surrounded and besieged by Confederate troops. The fort was running out of supplies, and Lincoln decided to send a fleet carrying food and provisions to resupply the fort.
However, in a message relayed by Confederate authorities, Lincoln informed them that the fleet carrying the supplies would not carry any troops or weapons, explicitly stating that their mission was purely to replenish the fort's dwindling supplies. This action was taken to avoid escalating the conflict and to give a chance for diplomacy before any military escalation occurred. However, the Confederate forces attacked the fort before the supplies arrived, resulting in the commencement of the American Civil War.