Creating a single combined plot with your current data set up would look something like this
p <- ggplot() +
# blue plot
geom_point(data=visual1, aes(x=ISSUE_DATE, y=COUNTED)) +
geom_smooth(data=visual1, aes(x=ISSUE_DATE, y=COUNTED), fill="blue",
colour="darkblue", size=1) +
# red plot
geom_point(data=visual2, aes(x=ISSUE_DATE, y=COUNTED)) +
geom_smooth(data=visual2, aes(x=ISSUE_DATE, y=COUNTED), fill="red",
colour="red", size=1)
however if you could combine the data sets before plotting then ggplot will automatically give you a legend, and in general the code looks a bit cleaner
visual1$group <- 1
visual2$group <- 2
visual12 <- rbind(visual1, visual2)
p <- ggplot(visual12, aes(x=ISSUE_DATE, y=COUNTED, group=group, col=group, fill=group)) +
geom_point() +
geom_smooth(size=1)