Developments in face-hardened armour in the late nineteenth and early to mid-twentieth centuries revealed that such armour was less effective against glancing oblique impacts.
dɪvˈɛləpmənts ɪn fˈeɪshˈɑːɹdənd ˈɑːɹmɚɹ ɪnðə lˈeɪt nˈaɪntiːnθ ænd ˈɜːli tə mˈɪdtwˈɛntiəθ sˈɛntʃɚɹiz ɹᵻvˈiːld ðæt sˈʌtʃ ˈɑːɹmɚ wʌz lˈɛs ɪfˈɛktɪv ɐɡˈɛnst ɡlˈænsɪŋ oʊblˈiːk ˈɪmpækts.